A torque transmission mechanism comprising: a transmission mechanism portion that includes an input shaft , an output shaft , and an intermediate portion including a connection portion and transmits input torque input into the input shaft to the output shaft through the intermediate portion ; and a limiting mechanism portion that is capable of switching between a connection state where the limiting mechanism portion is connected to the connection portion and a disconnection state where the limiting mechanism portion is disconnected from the connection portion and allows the rotation of the intermediate portion , and switches to the disconnection state when torque of at least a predetermined value acts in the connection state, wherein the limiting mechanism portion includes a switching portion that is movable to a connection position where the switching portion engages with the connection portion in the connection state and a disconnection position (P2)where the switching portion disengages from the connection portion in the disconnection state, and a torque limiting portion that supports the switching portion and allows movement of the switching portion toward the disconnection position (P2) when the torque of at least the predetermined value acts on the switching portion at the connection position (P1); characterized in that the limiting mechanism portion limits rotation of the intermediate portion in the connection state, and in that the torque limiting portion is configured to move the switching portion to an evacuation position (P3) where the switching portion is separate from the connection portion when the switching portion reaches the disconnection position (P2) where the switching portion comes into contact with the connection portion . a transmission mechanism portion that includes an input shaft , an output shaft , and an intermediate portion including a connection portion and transmits input torque input into the input shaft to the output shaft through the intermediate portion ; and a limiting mechanism portion that is capable of switching between a connection state where the limiting mechanism portion is connected to the connection portion and a disconnection state where the limiting mechanism portion is disconnected from the connection portion and allows the rotation of the intermediate portion , and switches to the disconnection state when torque of at least a predetermined value acts in the connection state, wherein the limiting mechanism portion includes a switching portion that is movable to a connection position where the switching portion engages with the connection portion in the connection state and a disconnection position (P2)where the switching portion disengages from the connection portion in the disconnection state, and a torque limiting portion that supports the switching portion and allows movement of the switching portion toward the disconnection position (P2) when the torque of at least the predetermined value acts on the switching portion at the connection position (P1); characterized in that the limiting mechanism portion limits rotation of the intermediate portion in the connection state, and in that the torque limiting portion is configured to move the switching portion to an evacuation position (P3) where the switching portion is separate from the connection portion when the switching portion reaches the disconnection position (P2) where the switching portion comes into contact with the connection portion . <EOS>