A tensioner comprising a solid cylindrical fixed member to be fixedly attached to a stationary portion, a movable eccentric member in the form of a solid cylinder and eccentrically rotatably provided around the fixed member, an idler in the form of a hollow cylinder and rotatably provided around the movable eccentric member for contact with a wrapping connector driving member, and a spring provided between the stationary portion and the movable eccentric member for biasing the eccentric member in a direction to press the idler into contact with the wrapping connector driving member. A high-viscosity oil is provided in a clearance between the outer periphery of the fixed member and the inner periphery of the movable eccentric member.