To provide a rotary pump having excellent durability and capable of preventing the contamination of the gas to be compressed with the lubricating oil, and to provide a divided gas engine using the fuel gas compressed by this rotary pump.

A rotary pump 28 is formed by arranging a fixed casing 72 in an outside case 70, and eccentrically supporting a rotary shaft 71 with the outside case 70 freely to be rotated, and installing partitioning wall vanes 75 freely to be put in/out of groove holes 74 formed in the rotary casing 73 fixed to the rotary shaft 71. The fixed casing 72 and the partitioning wall vanes 75 are made of the compound material having a low coefficient of friction and composed of porous ceramics such as SiC, Si3N4 and polyfluoroethylene or the hard grease intruded in a porous part of the porous ceramics.