To provide a rotary pump capable of making high compression and durability effective without lowering the reliability of an compressing element.

The rotary pump is provided with an oil collecting pan at a bottom portion, and a contacting surface portion 4 for changing an orientation of a tip end of a reciprocating partition plate 5 that is the compressing element of a compressing mechanism having an upper part of a crank shaft 3 as an input shaft according to eccentric rotations of a roller 2. A crank is provided at a lower part of the crank shaft 3 so as to make that part slidably contact at all times, and so as not to prevent a contact surface portion 4 from coming off at the time of compression. An arm is provided in a reversed L-shape at a rear part lower side of the reciprocating partition plate 5. A reciprocating partition plate arm shaft 8 is provided there and coupled by the coupling rod 27. The contact surface 4 is surface-contacted with the roller 2, and an oil groove 28 is directly provided on an upper side of an eccentric portion 33 from a center hole of the crank shaft 3 to a side 3 in a radius direction. And a circular oil groove 34 communicating to the oil groove 28 is provided. The oil groove 34 is provided to a four-surface oil groove 39 provided in a guiding groove 15 four-surface inside of an upper plate 10 which communicates the circular oil groove 34. Each oil groove is communicated to an oil hole 17.