In Fe0.75Mn1.35As compound, a metamagnetic transition from an antiferromagnetic phase to a ferrimagnetic phase can be induced above its phase transition temperature T (s) = 165 K by an external magnetic field, which leads to large magnetocaloric effects around T (s). The sign of the magnetic entropy change Delta S (M) in the Fe0.75Mn1.35As compound is negative, not as expected as an inverse magnetocaloric effect, and the maximum value of Delta S (M) is 4.2 J/kg K at 167.5 K for a magnetic field change of 5 T. Although it induces an irreversible lattice expansion, the cycling of a magnetic field does not induce an irreversible change in the magnetic transitions and magnetocaloric behaviors. The antiferromagnetism-related metamagnetic transitions with a large magnetic entropy change may provide with an opportunity in searching novel materials for magnetic refrigeration.