To provide a motion transmitting mechanical element whereby whether the motion transmitting mechanical element used in a machine has a surplus life or not can be visually easily judged, in the case of intending to regenerate the machine.

In a motion transmitting mechanical element 1 having a tooth 3 meshing together, a standard shape part C expecting a wear amount specifying a life for ensuring performance at the operated time or a wear amount including the rest of life in this wear amount is provided in a side surface. In this way, in the case of regenerating a machine, by confirming the standard shape part C, whether the rest of life is provided or not can be visually easily judged.