To impart a small and light structure, a smooth movement and superior mountability on a machine to a multiple cylinder reciprocating engine mechanism of high pressure, low speed and long stroke applying a hypocycloid planetary gear mechanism.

A method for coping with a V-arrangement two-cylinder cycloid reciprocating engine by a planetary gear double eccentric disk and one-crank pin is devised in this hypocycloid planetary gear mechanism by noticing that an arbitrary point on a reference pitch circle of a planetary gear created by the hypocycloid planetary gear mechanism having a tooth number ratio between a stationary inner gear and the planetary gear of 2:1 performs a linear reciprocal movement. By this method, a structure of a two-cylinder one-crank pin type hypocycloid planetary gear mechanism for the multiple cylinder reciprocating engine using a center planetary gear double eccentric disk as the planetary gear double eccentric disk is devised. By using the structure, mechanisms of 2n (n is a natural number) cylinder two-stroke and four-stroke cycloid reciprocating engines are constituted. Further, to enhance adaptability to various kinds of uses of the mechanisms, an end part planetary gear double eccentric disk and a split mold center planetary gear double eccentric disk are devised as the planetary gear double eccentric disks.