To provide a reversible gear pump capable of maintaining an optimal clearance on a side surface of a gear with a simple structure without adding a selector valve.

This reversible gear pump comprises a side plate 33 provided to face one side of a driving gear 35 and a following gear 36 and to be displaceable in an axial direction with both gears; a pressure receiving chamber 42 formed between a rear surface of the side plate 33 and a cover 34; and a through-hole 47 for introducing discharge liquid pressure to the pressure receiving chamber 42. A discharge liquid pressure intake port a of the through hole 47 is formed in a middle portion between a rotation center Q1 of the driving gear 35 and a rotation center Q2 of the following gear 36.