An A/D conversion device, comprising: a control section comprising an A/D port, a first output port, a second output port, a third output port, the control section being configured to control a first switching circuit by the first output port and a second switching circuit by the second output port; the A/D port being configured to convert a first analog voltage of a first object and a second analog voltage of a second object to digital quantities; the first switching circuit and the second switching circuit being connected to the A/D port, wherein the first analog voltage is output through a first series resistor via the first switching circuit to the A/D port and the second analog voltage is output through a second series resistor via the second switching circuit to the A/D port; a power source (Vcc); a first resistor and a second resistor, wherein the first resistor is connected with one terminal to the A/D port and with another terminal to the power supply (Vcc), and the second resistor is connected with one terminal to the A/D port and with another terminal to the third output port; wherein the control section is configured to generate a first mode in which the first and second analog voltages of the objects (4, 5) are output one by one independently to the A/D port by controlling the first switching circuit and the second switching circuit, a second mode in which none of the first and second analog voltages of the objects (4, 5) are output, a third mode in which none of the first and second analog voltages of the objects (4, 5) are output and the output to the A/D port is divided by the first resistor and the second resistor, a fourth mode in which the first and second analog voltages of the objects (4, 5) are output at the same time to the A/D port, wherein in the first mode, the third output port is set to high impedance, and A/D conversion values of the objects (4, 5) are acquired individually, in the second mode, the third output port is set to high impedance, and an anomaly of the A/D conversion device is detected when a voltage other than the voltage of the power source (Vcc) is inputted into the A/D port, in the third mode, the third output port is set to low, and an anomaly of one of the resistors (8,10) connected to the A/D port is detected based on the A/D conversion values, and in the fourth mode, the third output port is set to high impedance, and an anomaly of the first series resistors, or the second series resistor, or the first switching circuit, or the second switching circuit, or the first output port, or the second output port is detected based on the A/D conversion values. a control section comprising an A/D port, a first output port, a second output port, a third output port, the control section being configured to control a first switching circuit by the first output port and a second switching circuit by the second output port; the A/D port being configured to convert a first analog voltage of a first object and a second analog voltage of a second object to digital quantities; the first switching circuit and the second switching circuit being connected to the A/D port, wherein the first analog voltage is output through a first series resistor via the first switching circuit to the A/D port and the second analog voltage is output through a second series resistor via the second switching circuit to the A/D port; a power source (Vcc); a first resistor and a second resistor, wherein the first resistor is connected with one terminal to the A/D port and with another terminal to the power supply (Vcc), and the second resistor is connected with one terminal to the A/D port and with another terminal to the third output port; wherein the control section is configured to generate a first mode in which the first and second analog voltages of the objects (4, 5) are output one by one independently to the A/D port by controlling the first switching circuit and the second switching circuit, a second mode in which none of the first and second analog voltages of the objects (4, 5) are output, a third mode in which none of the first and second analog voltages of the objects (4, 5) are output and the output to the A/D port is divided by the first resistor and the second resistor, a fourth mode in which the first and second analog voltages of the objects (4, 5) are output at the same time to the A/D port, wherein in the first mode, the third output port is set to high impedance, and A/D conversion values of the objects (4, 5) are acquired individually, in the second mode, the third output port is set to high impedance, and an anomaly of the A/D conversion device is detected when a voltage other than the voltage of the power source (Vcc) is inputted into the A/D port, in the third mode, the third output port is set to low, and an anomaly of one of the resistors (8,10) connected to the A/D port is detected based on the A/D conversion values, and in the fourth mode, the third output port is set to high impedance, and an anomaly of the first series resistors, or the second series resistor, or the first switching circuit, or the second switching circuit, or the first output port, or the second output port is detected based on the A/D conversion values.