a forward - drive apparatus for a bicycle comprises a drive transferring portion 40 including a pedal 20 fixed to a pedal shaft 22 of a bicycle and for transferring the drive force to a drive sprocket 30 connected by means of a chain to a rear wheel ; a drive switching portion 50 for enabling the drive force generated from the drive transferring portion 40 to rotate the rear wheel in a forward or idle state ; and a drive coupling portion 60 for enabling the forward or idle rotation of the drive sprocket 30 according to the operation of the drive switching portion 50 and for working the bicycle in a forward or idle rotation according to the selection of a lever during the back - pedaling of the bicycle , thereby relieving user &# 39 ; s fatigues preventing the loss of the physical energy and enabling the well - muscled movement of legs in every - day life .