The present invention relates to a delta Y-type crank of a bicycle including: a pair of diameter cranks connected to both ends of a crank shaft of a driving chain gear constituting a power unit of a bicycle; and a Y-type crank integrated on the respective both end of the diameter crank. An existing rod-type crank which connects the shaft of the driving chain gear of a bicycle with pedals which are stamping devices can be replaced with the delta Y-type crank of a bicycle of the present invention to simultaneously generate both a moment of rotation and a moment of a couple, thus reducing the stamping force of feet applied to the pedals and preventing the feet force loss.
