To provide a rotary motion transmitting mechanism which can enhance the convenience in use, the manufacturing facility, the durability, the torque transmission characteristic and the like.

A rotary motion transmitting mechanism is composed of gears 20-1, 20-2 respectively having rotary shafts 21-1, 20-2, a rotary member 30 adapted to be rotated around a rotary shaft 33 which is different from the rotary shafts 21-1, 21-2, and a member 10 formed thereon with a rack 11 adapted to be meshed with the gears 20-1, 20-2, and adapted to be rotated around a rotary shaft 11 extending in a direction crossing the teeth of the rack 11, rotary motion being transmitted between the rotary member 30 and the member 10 formed therein with the rack 11. The number of the gears 20-1, 20-2 is plural (2), and are rotatably journalled to the rotary member 30 so as to be rotatable around the shafts 21-1, 21-2 located at different positions.