PURPOSE: To reduce abrasion by undercut a cam face to the extent, in which an entraining member is not brought into contact with the cam face, excepting a connection area around a cam reversing point in a driving device for motion mechanically entraining a reciprocated part by means of a cam.

CONSTITUTION: This driving device for motion is provided with at least one closed cams 40, 43 in a rotationally derivable cam supporting body 33 for mechanically entraining a reciprocated part, and entrainment is carried out by cooperating rollers 26, 27 supported in rotary shafts 30, 31 in the reciprocated part with each other, or alternatively, by means of entraining members 34, 35 connected to cam faces 28, 29, 38, 39 provided with rolls. In the cams 40, 43, their cam faces opposed to the motion direction 37 of the reciprocated part at that time are undercut at least to the extent in which the entraining members 34, 35 are not bought into contact with them in this area excepting a slight connection areas 41, 42 around cam reversing points O.T,U.T. In this way, abrasion can be reduced, and excessive increase in a cam production precision is not needed.