The invention provides a hobbing device for a gear, and belongs to the technical field of gear processing equipment. The device comprises a gear clamping device and a hobbing processing device, wherein a main shaft pulling rod of the gear clamping device is arranged on a clamp body and a turntable in an up-down sliding manner; a gyrating connecting clamping block at the lower end of the main shaftpulling rod is rotatably clamped to a gyrating connecting clamping slot; a driving gear is engaged with a driven gear; an inner conical surface of an expansion sleeve clings to an outer conical surface of the upper end of the clamp body; the expansion sleeve is compressed through an expansion sleeve pressing plate; a discharging pulling rod penetrates a stress concentration hole and a dischargingpulling rod hole so as to realize the connection of the expansion sleeve and the main shaft pulling rod; the gear is axially locked through an upper locking nut and a lower locking nut; an X-direction lead screw and a Y-direction lead screw of the hobbing processing device are in thread connection; a Y-direction lead screw and a Y-direction lead screw nut are in thread connection; and a hobbing is coaxially mounted on a hobbing supporting shaft. With the adoption of the device, the gear hobbing can be rapidly processed, and the gear is conveniently mounted and dismounted.