PURPOSE: To provide a tenoning device capable of efficiently performing female tenon working of both side faces or either one side face in the longitudinal direction of the lumber to be worked while permitting manpower saving.

CONSTITUTION: The elevating/lowering bases 9a, 9b are equipped with a first cutters 18a, 18b and a second cutters 19a, 19b. The bases 9a, 9b are provided at a pair in the right and left in the upside of the lumber W to be worked which is centripetally clamped by a vice means F. A common driving motor 11 is linked to the bases 9a, 9b to interlockingly elevate/lower and move them. Further pneumatic cylinders are equipped in these bases 9a, 9b and actuate so as to change over the cutters in the cutting position and the evacuating position of the lumber W to be worked.