A joint mechanism that can be used in an articulated finger unit of a robot hand has first and second actuators that are disposed facing each other from the front and back on either side of a perpendicular joint axle, and first and second drive bevel gears that are coaxially connected and fixed to distal ends of output axles thereof. A driven bevel gear fixedly mounted in coaxial manner on the perpendicular joint axle meshes with the first and second drive bevel gears. The perpendicular joint axle is rotatably driven by the two actuators, and a revolving bracket connected thereto revolves to the left and right. The drive torque of the joint axle can be increased without increasing the outside diameter dimensions of the mechanism.