NOVELTY - A power supply device (10) comprises a battery for supplying electrical power to a propulsion motor of an electric vehicle; a capacitor (106) in parallel with the propulsion motor; a first connection contactor (104A) which connects/disconnects the connection of one pole and the motor of the battery; a second connection contactor (104B) which connects/disconnects the connection of the other pole and the motor of the battery; and a charge contactor (108B) which connects/disconnects the electrical power supplied to the capacitor by limiting resistance from the battery.    USE - Power supply device used for electric vehicle.    ADVANTAGE - The device can ensure increase of cooling time for reducing temperature in a charging circuit. This is achieved by interrupting the connection signal after the prescribed time based on the frequency of the on-state operation of the ignition operation part.    DETAILED DESCRIPTION - A power supply device (10) comprises a battery for supplying electrical power to a propulsion motor of an electric vehicle; a capacitor (106) arranged in parallel with the propulsion motor; a first connection contactor (104A) which connects/disconnects the connection of one pole and the motor of the battery; a second connection contactor (104B) which connects/disconnects the connection of the other pole and the motor of the battery; a charge contactor (108B) which connects/disconnects the electrical power supplied to the capacitor by limiting resistance from the battery; and a control part (110) for controlling the first and second connection contactors and the charge contactor. Based on a connection signal corresponding to an on-state operation of an ignition operation part (20), one of the connection contactors is connected to the charge contactor for a predetermined period of time. The control part prohibits the connection of the charge contactor after the predetermined period of time based on the frequency of the on-state operation of the ignition operation part.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic diagram of the power supply device. Drawing includes non-English language text.    Power supply device (10)    Ignition operation part (20)    First connection contactor (104A)    Second connection contactor (104B)    Capacitor (106)    Charge contactor (108B)    Control part (110)