To provide a portable key in which a joint part between a grip and a key blade is not damaged even when inserting the key into a keyhole of a cylinder lock of a lock for a fixture and performing unlock operation.

A holding member which holds a key blade 2 under a neutral state at a use position when the key blade 2 rotates in a projection direction and a holding spring member 23 are respectively provided at a tip part of a grip. In using the grip, when a load exceeding a set torque value determined by retention coefficients of a locking part of the holding member and a base end part of the key blade is applied to a cylindrical joint part between a support shaft 5 and the base end part 3a of the key blade in the turning operation of the grip while holding the grip, the key blade is tilted so as to release holding power of the holding member and against spring force of the holding spring member.