A control device for a vehicle, comprising: a control processing unit configured to control the vehicle; a monitor unit configured to monitor a state of the vehicle and a control state; and a nonvolatile storage unit, wherein the control processing unit comprises: a vehicle control part configured to: input a plurality of pieces of vehicle state information on the state of the vehicle; calculate a control amount, which is control state information, from the vehicle state information; output a control signal for controlling a controlled device; and use the monitor unit to monitor the control state; an abnormality detection part configured to detect an abnormality based on a state where the vehicle state information or the control state information exists in an abnormality region in which the vehicle state information or the control state information has not reached a failure region corresponding to a failure; and a data storage control part configured to: store, in a buffer included in the control processing unit, the vehicle state information, the control state information, and monitor information for a period set in advance while always updating the latest vehicle state information, control state information, and monitor information; and store in the nonvolatile storage unit, when the abnormality is detected, the vehicle state information, the control state information, and the monitor information before and after the abnormality detection including the information stored in the buffer; wherein the data storage control part is configured to store the vehicle state information, the control state information, and the monitor information in accordance with a stored table indicating types of data to be stored, a number of digits of the stored data, and a frequency of storage for each type of abnormality. a control processing unit configured to control the vehicle; a monitor unit configured to monitor a state of the vehicle and a control state; and a nonvolatile storage unit, wherein the control processing unit comprises: a vehicle control part configured to: input a plurality of pieces of vehicle state information on the state of the vehicle; calculate a control amount, which is control state information, from the vehicle state information; output a control signal for controlling a controlled device; and use the monitor unit to monitor the control state; an abnormality detection part configured to detect an abnormality based on a state where the vehicle state information or the control state information exists in an abnormality region in which the vehicle state information or the control state information has not reached a failure region corresponding to a failure; and a data storage control part configured to: store, in a buffer included in the control processing unit, the vehicle state information, the control state information, and monitor information for a period set in advance while always updating the latest vehicle state information, control state information, and monitor information; and store in the nonvolatile storage unit, when the abnormality is detected, the vehicle state information, the control state information, and the monitor information before and after the abnormality detection including the information stored in the buffer; a vehicle control part configured to: input a plurality of pieces of vehicle state information on the state of the vehicle; calculate a control amount, which is control state information, from the vehicle state information; output a control signal for controlling a controlled device; and use the monitor unit to monitor the control state; input a plurality of pieces of vehicle state information on the state of the vehicle; calculate a control amount, which is control state information, from the vehicle state information; output a control signal for controlling a controlled device; and use the monitor unit to monitor the control state; an abnormality detection part configured to detect an abnormality based on a state where the vehicle state information or the control state information exists in an abnormality region in which the vehicle state information or the control state information has not reached a failure region corresponding to a failure; and a data storage control part configured to: store, in a buffer included in the control processing unit, the vehicle state information, the control state information, and monitor information for a period set in advance while always updating the latest vehicle state information, control state information, and monitor information; and store in the nonvolatile storage unit, when the abnormality is detected, the vehicle state information, the control state information, and the monitor information before and after the abnormality detection including the information stored in the buffer; store, in a buffer included in the control processing unit, the vehicle state information, the control state information, and monitor information for a period set in advance while always updating the latest vehicle state information, control state information, and monitor information; and store in the nonvolatile storage unit, when the abnormality is detected, the vehicle state information, the control state information, and the monitor information before and after the abnormality detection including the information stored in the buffer; wherein the data storage control part is configured to store the vehicle state information, the control state information, and the monitor information in accordance with a stored table indicating types of data to be stored, a number of digits of the stored data, and a frequency of storage for each type of abnormality.