A steering lock device (1) includes a camshaft (24) including a shaft portion (24) having an axis (L1), a lock actuation cam (41) that radially projects from a first position of the shaft portion (24) in an axial direction, and a projection (43) that radially projects from a second position of the shaft portion (24) in the axial direction; a housing (2) rotatably accommodating the camshaft (24); and a lock bar (22) moved by the lock actuation cam (41) in a locking direction or an unlocking direction when the camshaft (24) is rotated about the axis (L1) when a key cylinder (7) is operated by a mechanical key (80).The camshaft (24) is configured so that the projection (43) is separated from the shaft portion (24) if a load exceeding a predetermined strength acts on the projection (43) of the camshaft (24).