We report the observation of highly nondegenerate four-wave mixing from a semiconductor microcavity. The phase mismatch originating from the unique relationship between a beam incidence angle and its cavity resonance frequency was minimized by using a new method where both of pump and probe beams are obliquely incident. External efficiency of 1.6&percent; was measured at 10 K for 1.5 THz frequency conversion of probe pulses by using 1 ps pump pulses of 55 pJ incident pulse energy. ©1997 American Institute of Physics.