An air conditioning controller that controls an air conditioner that adjusts a temperature of a target space, wherein the air conditioning controller has, as a control mode, a first mode in which the air conditioner performs a preheating operation or a precooling operation at or after a first time (te) set in advance and at or before a second time (ts) at which the target space is used next, the first mode is control of operating the air conditioner and stopping the air conditioner when the temperature of the target space increases to a preheating temperature (T H) higher than a target temperature (T M) of the target space at the second time (ts) or when the temperature of the target space decreases to a precooling temperature (T L) lower than the target temperature (T M), the preheating temperature (T H) is set such that the temperature of the target space becomes the target temperature (T M) or higher than the target temperature (T M) at a point of the second time (ts) due to a decrease of the temperature of the target space after the air conditioner stops in the first mode, and the precooling temperature (T L) is set such that the temperature of the target space becomes the target temperature (T M) or lower than the target temperature (T M) at the point of the second time (ts) due to an increase of the temperature of the target space after the air conditioner stops in the first mode, wherein the air conditioning controller (50, 55) has a second mode as a control mode together with the first mode, in a case where the first mode is a control mode in which the air conditioner performs the preheating operation, the second mode is a control mode in which the air conditioner is operated from a temperature lower than the target temperature (T M) at the second time (ts) to increase the temperature of the target space to the target temperature (T M), in a case where the first mode is a control mode in which the air conditioner performs the precooling operation, the second mode is a control mode in which the air conditioner is operated from a temperature higher than the target temperature (T M) at the second time (ts) to decrease the temperature of the target space to the target temperature (T M), and the air conditioning controller (50, 55) selects and executes either the first mode or the second mode based on a predetermined determination criterion. the air conditioning controller has, as a control mode, a first mode in which the air conditioner performs a preheating operation or a precooling operation at or after a first time (te) set in advance and at or before a second time (ts) at which the target space is used next, the first mode is control of operating the air conditioner and stopping the air conditioner when the temperature of the target space increases to a preheating temperature (T H) higher than a target temperature (T M) of the target space at the second time (ts) or when the temperature of the target space decreases to a precooling temperature (T L) lower than the target temperature (T M), the preheating temperature (T H) is set such that the temperature of the target space becomes the target temperature (T M) or higher than the target temperature (T M) at a point of the second time (ts) due to a decrease of the temperature of the target space after the air conditioner stops in the first mode, and the precooling temperature (T L) is set such that the temperature of the target space becomes the target temperature (T M) or lower than the target temperature (T M) at the point of the second time (ts) due to an increase of the temperature of the target space after the air conditioner stops in the first mode, wherein the air conditioning controller (50, 55) has a second mode as a control mode together with the first mode, in a case where the first mode is a control mode in which the air conditioner performs the preheating operation, the second mode is a control mode in which the air conditioner is operated from a temperature lower than the target temperature (T M) at the second time (ts) to increase the temperature of the target space to the target temperature (T M), in a case where the first mode is a control mode in which the air conditioner performs the precooling operation, the second mode is a control mode in which the air conditioner is operated from a temperature higher than the target temperature (T M) at the second time (ts) to decrease the temperature of the target space to the target temperature (T M), and the air conditioning controller (50, 55) selects and executes either the first mode or the second mode based on a predetermined determination criterion.