Disclosed is a torus crank mechanism including a housing assembly (100) providing sealed chambers (145 to 148), a core (200) centrally arranged in the housing assembly while having a vertical shaft (215 or 216) protruded from one or each of upper and lower surfaces of the core, and horizontal shafts (211 to 214), a rotor (300) adapted to rotate in a reciprocating fashion around the core while having rotating vanes (311 to 314) arranged in respective chambers, and guide slots (315 to 318), bevel gears (410 to 440) rotatably supported by respective horizontal shafts while having respective eccentric sliders (411, 421, 431, and 441) rotatably and slidably received in the guide slots, and an output gear (500 or 600) rotatably supported by the vertical shaft. A multiple torus crank mechanism is configured by coaxially connecting torus crank mechanisms each having the above described configuration.