The purpose of this study is investigating efficacy of a magnetic cam which can drive without contact. In general cams, existence of contact between a cam disk and a cam follower causes frictional wear and needs lubrication. On the other hand, the magnetic cam is composed of a cam disk whose rim is a permanent magnet and a magnetic cam follower. It drives by repulsion between magnets of the disk and the follower. Therefore, contact of the system can be removed. Evaluating effectiveness of a magnetic cam system, we derived an equation of motion of the cam follower and conducted numerical calculation of it. As a result, it is confirmed that the magnetic cam system can convert rotational motion into reciprocating motion at low rotational speed. Thus it can be concluded that a magnetic cam is useful at low rotational speed.