One of two connector receiving parts of a processor for endoscope has a shutter mechanism configured to open a shutter by an external force, the shutter having a gap through which a connector-side connection end section passes, and being configured to partition a recessed space of the connector receiving part with respect to an outside. In addition, the processor for endoscope includes a lock mechanism configured to make the shutter into the locked state during a period when another connection end section on the connector side and a processor-side connection end section are connected, and release the locked state of the shutter when the connection between the other connection end section on the connector side and the processor-side connection end section is released.