To provide a ring lock for a bicycle for further smoothly performing operation in unlocking while improving crime preventive performance.

An unlocking mechanism part 5 for journaling triple gears 7 is arranged in a lower part of one seesaw type button. The gears 7 are rotated by suspending a gear stopper of the unlocking mechanism part 5 by pushing down one end of the seesaw type button, and the gears 7 are locked when the gear stopper is restored. The respective gears 7 are successively made to reach an unlocking position by respectively pushing down both ends of the seesaw type button 3 by a predetermined frequency, and can be unlocked by moving an unlocking plate 12 and a bolt lock plate 15 by pushing an unlocking time exclusive button 2. When a bolt slides up to a locking position in locking, an automatic lock plate 17 pivoted on a lock body engages with a projection part of a bolt outer peripheral part, and the gears 7 are rotated except for the unlocking position, and the unlocking mechanism part 5 is automatically put in a locking state. In unlocking, unlocking operation can be started by resetting the unlocking mechanism part 5 by pushing a reset button 4 in a plurality of times.