A power supply circuit breaking device comprising: a first connector housing; a second connector housing that is configured to be fitted to and separated from the first connector housing, and that includes a lever rotatably supported; a main lock unit that is configured by a main lock claw formed on an outer peripheral tubular portion of the second connector housing and a main lock hole formed on the lever and that locks in a finally fitted state in which the second connector housing is completely fitted to the first connector housing by engaging the main lock claw of the second connector housing with the main lock hole of the lever; a sub-lock unit that is configured by a sub-lock claw provided to protrude to an outer surface of the first connector housing and an operation portion provided on the second connector housing and that locks in a temporarily fitted state in which the second connector housing is displaced toward a separating direction from the finally fitted state and a part thereof is fitted to the first connector housing by entering the sub-lock claw of the first connector housing into an engaging hole formed in an engaging plate portion of the operation portion of the second connector housing; a main switch unit (MSw) that is configured to be switched on in the finally fitted state and the temporarily fitted state; and a sub-switch unit (SSw) that is configured to be switched on in the finally fitted state and switched off in the temporarily fitted state, characterized in that the lever supported by the second connector housing is rotatable to one end of the second connector housing into the finally fitted state in which the second connector housing is completely fitted to the first connector housing by engaging the main lock claw of the second connector housing with the main lock hole of the lever, and the sub-lock unit is provided at another end of the second connector housing. a first connector housing; a second connector housing that is configured to be fitted to and separated from the first connector housing, and that includes a lever rotatably supported; a main lock unit that is configured by a main lock claw formed on an outer peripheral tubular portion of the second connector housing and a main lock hole formed on the lever and that locks in a finally fitted state in which the second connector housing is completely fitted to the first connector housing by engaging the main lock claw of the second connector housing with the main lock hole of the lever; a sub-lock unit that is configured by a sub-lock claw provided to protrude to an outer surface of the first connector housing and an operation portion provided on the second connector housing and that locks in a temporarily fitted state in which the second connector housing is displaced toward a separating direction from the finally fitted state and a part thereof is fitted to the first connector housing by entering the sub-lock claw of the first connector housing into an engaging hole formed in an engaging plate portion of the operation portion of the second connector housing; a main switch unit (MSw) that is configured to be switched on in the finally fitted state and the temporarily fitted state; and a sub-switch unit (SSw) that is configured to be switched on in the finally fitted state and switched off in the temporarily fitted state, characterized in that the lever supported by the second connector housing is rotatable to one end of the second connector housing into the finally fitted state in which the second connector housing is completely fitted to the first connector housing by engaging the main lock claw of the second connector housing with the main lock hole of the lever, and the sub-lock unit is provided at another end of the second connector housing.