A torque transmission apparatus (1, 1a) that is adapted to generate torque corresponding to a relative rotational speed between two shafts by using a shearing force of a viscous fluid so as to reduce a speed difference, the torque transmission apparatus (1, 1a) comprising: a case member that forms an operation chamber that contains the viscous fluid; a shaft that is inserted through the case member so as to be capable of rotating relative to the case member; a plurality of first plates that are connected to the case member; and a plurality of second plates (5, 5X, 5Y) that are connected to the shaft and provided spaced apart from the first plates in a thickness direction, characterized in that the second plates (5, 5X, 5Y) are movable plates capable of swinging within a plane perpendicular to an axis of the shaft, and the first plates are attached to an inner circumferential surface of the case member, and the movable plates (5, 5X, 5Y) are swingably supported about a position at a distance from the rotational axis of the shaft, wherein the movable plates (5, 5X, 5Y) are held at a first position, at which an interlocking area between the first plates and the movable plates (5, 5X, 5Y) is small, by an elastic member (6, 6a) when a relative rotational speed between the case member and the shaft is small, and when the relative rotational speed between the case member and the shaft exceeds a predetermined value, the movable plates (5, 5X, 5Y) are pivotally moved toward the first plates by the shearing force of the viscous fluid generated between plates by relative rotation, and held at a second position at which the interlocking area between the movable plates (5, 5X, 5Y) and the first plates is large, so as to switch the interlocking area between the between the first plates and the movable plates (5, 5X, 5Y) and control a value of torque generated between the case member and the shaft. a case member that forms an operation chamber that contains the viscous fluid; a shaft that is inserted through the case member so as to be capable of rotating relative to the case member; a plurality of first plates that are connected to the case member; and a plurality of second plates (5, 5X, 5Y) that are connected to the shaft and provided spaced apart from the first plates in a thickness direction, characterized in that the second plates (5, 5X, 5Y) are movable plates capable of swinging within a plane perpendicular to an axis of the shaft, and the first plates are attached to an inner circumferential surface of the case member, and the movable plates (5, 5X, 5Y) are swingably supported about a position at a distance from the rotational axis of the shaft, wherein the movable plates (5, 5X, 5Y) are held at a first position, at which an interlocking area between the first plates and the movable plates (5, 5X, 5Y) is small, by an elastic member (6, 6a) when a relative rotational speed between the case member and the shaft is small, and when the relative rotational speed between the case member and the shaft exceeds a predetermined value, the movable plates (5, 5X, 5Y) are pivotally moved toward the first plates by the shearing force of the viscous fluid generated between plates by relative rotation, and held at a second position at which the interlocking area between the movable plates (5, 5X, 5Y) and the first plates is large, so as to switch the interlocking area between the between the first plates and the movable plates (5, 5X, 5Y) and control a value of torque generated between the case member and the shaft.