A mechanical key is to be prevented from coming apart, a head portion of the mechanical key is to be attached to a main body for use and the main body is to be prevented from being disassembled unintentionally when using the mechanical key. In a key lock structure of a mechanical key of a portable device in which a mechanical key is storable in a main body, the main body is configured in a two-piece structure including a first case and a second case, the first case includes a first storage section for storing the mechanical key and a second storage section for storing a key lock mechanism of the mechanical key, the lock mechanism locks the mechanical key stored in the first storage section to prevent the mechanical key from coming off and unlocks in response to a predetermined operation to allow the mechanical key to be pulled out.