PURPOSE: To provide a forward driving mechanism for a bicycle which can reduce fatigue of a user and can prevent the loss of physical energy and enables sufficient muscular motion in a daily life.

CONSTITUTION: A forward driving mechanism for a bicycle is composed of a driving transmitting part 40 which contains a pedal 20 installed on a pedal shaft 22 of a bicycle and is formed to transmit driving force to a driving sprocket 30 connected to a rear wheel by a chain, a driving switching part 50 to enable a forward or idle rotation of the rear wheel by driving force made from the driving transmitting part 40 and a driving joining part 60 to enable a forward or inverse rotation of the driving sprocket 30 according to actuation of the driving switching part 50. During back pedaling of the bicycle, the bicycle is forward or idly rotated according to selection of a lever.