A power circuit shut off device (1, 1A) comprising: a housing (10, 10A); a switch portion (MSw) that is provided in the housing (10, 10A); and an operating member (80, 80A) configured to turn on or turns off the switch portion (MSw), wherein the switch portion (MSw) comprising: a pair of terminals arranged along a bottom face of the housing (10, 10A); an electric conductive member having contact point portions and that is elastically urged toward the pair of terminals, wherein the pair of terminals are brought into an electric conductive state to each other when the pair of terminals contact the contact point portions respectively; and an insulating movable member configured to move along a direction in which the pair of terminals are arranged, and that is made of insulating material; wherein the insulating movable member is moved between a shut-off position and a conductive position by an operation on the operating member (80, 80A), the insulating movable member in the shut-off position being put between the contact point portions of the electric conductive member and the terminals so as to turn off the switch portion (MSw), and the insulating movable member in the conductive position being released from between the contact point portions of the electric conductive member and the terminals so as to turn on the switch portion (MSw), the power circuit shut off device (1, 1A) characterized by further comprising: a sub-switch portion (SSw) that is turned on together with the switch portion (MSw) in a conductive state in which the insulating movable member is disposed in the conductive position, and is turned off to shut off electric conduction to a circuit of the switch portion (MSw) in a temporary shut-off state in which the switch portion (MSw) is kept on when the insulating movable member is being displaced toward the shut-off position. a housing (10, 10A); a switch portion (MSw) that is provided in the housing (10, 10A); and an operating member (80, 80A) configured to turn on or turns off the switch portion (MSw), wherein the switch portion (MSw) comprising: a pair of terminals arranged along a bottom face of the housing (10, 10A); an electric conductive member having contact point portions and that is elastically urged toward the pair of terminals, wherein the pair of terminals are brought into an electric conductive state to each other when the pair of terminals contact the contact point portions respectively; and an insulating movable member configured to move along a direction in which the pair of terminals are arranged, and that is made of insulating material; a pair of terminals arranged along a bottom face of the housing (10, 10A); an electric conductive member having contact point portions and that is elastically urged toward the pair of terminals, wherein the pair of terminals are brought into an electric conductive state to each other when the pair of terminals contact the contact point portions respectively; and an insulating movable member configured to move along a direction in which the pair of terminals are arranged, and that is made of insulating material; wherein the insulating movable member is moved between a shut-off position and a conductive position by an operation on the operating member (80, 80A), the insulating movable member in the shut-off position being put between the contact point portions of the electric conductive member and the terminals so as to turn off the switch portion (MSw), and the insulating movable member in the conductive position being released from between the contact point portions of the electric conductive member and the terminals so as to turn on the switch portion (MSw), the power circuit shut off device (1, 1A) characterized by further comprising: a sub-switch portion (SSw) that is turned on together with the switch portion (MSw) in a conductive state in which the insulating movable member is disposed in the conductive position, and is turned off to shut off electric conduction to a circuit of the switch portion (MSw) in a temporary shut-off state in which the switch portion (MSw) is kept on when the insulating movable member is being displaced toward the shut-off position.