A three-rotational-degree-of-freedom connection mechanism required for a robot that can make motion similar to a human has a simple structure, and there is no restriction on motion within a movable range. The three-rotational-degree-of-freedom connection mechanism includes a joint connecting a second member rotatably to a first member with three rotational degrees of freedom including rotation around a torsion axis, three actuators each including variable length links having a variable length, and power sources for generating force changing the lengths of variable length links and three first-member-side link attaching units provided in first member and the second-member-side link attaching units provided on the second member such that variable length links having a twisted relationship with respect to a torsion axis exist in each state within a movable range of joint.