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.