PURPOSE: To enable the maintaining of a stable condition free from the elapsing of time by obtaining a state signal corresponding to condition of a memory circuit from a contact connection of a latching type relay.

CONSTITUTION: This circuit is provided with a memory circuit, a state of which changes each time an external signal is received and a data of a specified state is preset according to the closing of a power source or the return thereof and a latching type relay with a connection state switched according to the state of the memory circuit. The memory circuit therein used is, for example, an FF 3 and a latching relay 5 is provided which works corresponding to a state of the FF 3 and the updating of the state of an output signal of the relay 5 is performed with a switching of a memory state of the FF 3. A state signal corresponding to the switching state is held with the relay 5 while being fed to the FF 3 and this holding state is supplied as preset date of the FF 3. This enables the holding of a state corresponding to a change in the memory state of the FF 3 simultaneously.