A circuit abnormality diagnosis device that diagnoses a circuit abnormality in a safety device for a flight object including an igniter and a circuit connected to the igniter, the circuit abnormality diagnosis device comprising: a power supply capable of loading a test voltage to the circuit; a calculation unit that controls on/off of the power supply: characterized in that it further comprises: a first overcurrent prevention unit that is electrically connected in series to the power supply and prevents an overcurrent from flowing through the circuit; a voltage amplification unit that is configured to be electrically connected in parallel to the circuit and amplifies a voltage to a predetermined order; a voltage reading unit that is electrically connected in series to the voltage amplification unit and reads a value of the voltage amplified by the voltage amplification unit (hereinafter, the voltage value); and a second overcurrent prevention unit that is electrically connected in series to the voltage reading unit on an upstream side of the voltage reading unit and prevents an overcurrent from flowing, wherein the calculation unit receives information on the voltage value from the voltage reading unit, and determines that a case where the voltage value is within a range of a first voltage value V 1 or more and a second voltage value V 2 or less, which is set in advance as a range of voltage values indicating that the circuit is normal, is a normal state; a case where the voltage value is less than the voltage value V 1 is a short-circuit state in which the circuit is short-circuited; and a case where the voltage value is higher than the voltage value V 2 is a disconnection state in which the circuit is disconnected. a power supply capable of loading a test voltage to the circuit; a calculation unit that controls on/off of the power supply: characterized in that it further comprises: a first overcurrent prevention unit that is electrically connected in series to the power supply and prevents an overcurrent from flowing through the circuit; a voltage amplification unit that is configured to be electrically connected in parallel to the circuit and amplifies a voltage to a predetermined order; a voltage reading unit that is electrically connected in series to the voltage amplification unit and reads a value of the voltage amplified by the voltage amplification unit (hereinafter, the voltage value); and a second overcurrent prevention unit that is electrically connected in series to the voltage reading unit on an upstream side of the voltage reading unit and prevents an overcurrent from flowing, wherein the calculation unit receives information on the voltage value from the voltage reading unit, and determines that a case where the voltage value is within a range of a first voltage value V 1 or more and a second voltage value V 2 or less, which is set in advance as a range of voltage values indicating that the circuit is normal, is a normal state; a case where the voltage value is less than the voltage value V 1 is a short-circuit state in which the circuit is short-circuited; and a case where the voltage value is higher than the voltage value V 2 is a disconnection state in which the circuit is disconnected.