KEY CYLINDER DEVICE

A key cylinder device includes a rotor case that encloses a rotor operable to rotate by a mechanical key, the rotor being inserted into the rotor case from a direction opposite to an insertion direction of the mechanical key, a holding member including a pair of leg portions held by the rotor case, and a fixing member that protrudes from the holding member. The rotor case includes a fixing member-holding structure that the fixing member is held by the leg portions of the holding member at a temporary assembly position for temporarily assembling the fixing member in a retracted state without inwardly protruding beyond an inner surface of the rotor case and at an assembly position for assembling the fixing member in a state of inwardly protruding from the inner surface of the rotor case.