There is disclosed a continuously variable speed gear set including a driving input shaft, a carrier extended from one end of the driving input shaft to rotate integrally with the driving input shaft, a spindle gear provided in a predetermined portion of the carrier to relatively rotate with respect to the driving input shaft, the spindle gear comprising a shaft identical to the driving input shaft, a planetary gear arranged in the carrier, a driving output gear comprising a shaft arranged on the same line with the axis of the driving input shaft to relatively rotate, the driving output gear engaging with the planetary gear rotating and revolving along the rotation of the carrier to receive a rotation force from the planetary force, and a transmission input unit configured to control a rotation speed of the driving output gear by controlling a rotation speed of the spindle gear.