To provide a magnet lock for a bicycle allowing a number of combinations by properly selecting lock pin infixing holes and polarities of magnets.

A lock body 3 having plural circularly disposed lock pin infixing holes and a lock pin 6 inserted through a spring 7, and a spindle 2 rotatably provided to face the lock body 3 in which a magnet 5 of a larger diameter than the aperture of the lock pin infixing hole engaged and inserted at a position corresponding to the lock pin infixing hole are disposed in a main body case 1. A lock cam 4 is fixed to an axial end of the spindle 2, and by the reaction against a magnet M embedded in a key K, the magnet 5 is moved to push the lock pin 6 into the lock pin infixing hole in the lock body 3 against the urging force of the spring, thereby lock with the spindle 2 is released.