To provide a simple unified structure of high efficiency using rotary motion straight as circumferential transfer of a fluid.

This liquid transfer mechanism is provided with a casing provided with a pair of cylindrical spaces; a pair of rotors 1a, 1b coinciding in axes with the respective cylindrical spaces and synchronously rotated in reverse directions while abutting each other at the peripheral side parts; and an intake port 13a and a discharge port 13b opened to the respective cylindrical spaces and controlled interlocked with the rotation of the rotors 1a, 1b. Claw parts 11a, 11b and cutout parts 12a, 12b are formed at the respective peripheral side parts of the rotors 1a, 1b. The claw parts 11a, 11b are set to slidingly move with the respective tips abutting on the inner peripheries in the corresponding cylindrical spaces to partition both sides in the proceeding direction into spaces 20a, 20b following the rotation of the rotors 1a, 1b and to slidingly move along the peripheral surfaces of the cutout parts 12a, 12b of the object rotors 1a, 1b at the overlap part of the cylindrical spaces.