To reduce cost and improve operability by making a set of a transmitter and a receiver unlock remotely-unlocked type lock body attached to the front and rear wheels of a bicycle.

By providing two front and rear lock bodies 1a and 1b, each furnished with a motor for unlocking and mounted on the front and rear wheels, one receiver 3 incorporating a battery, receiving an unlocking signal and operating said motors and one remote transmitter 4 that sends an unlocking signal to the single receiver 3, the front and rear lock bodies 1a and 1b are released simultaneously by transmission and reception of the remote transmitter 4 and the receiver 3.