InP Schottky barrier solar cells are fabricated and the device parameters are measured under solar illumination. The barrier height of n-InP Schottky contact increases by surface oxidation in wet O2 atmosphere. The oxidation time can be decreased by surface treatment with bromine water. No surface oxidation is carried out for p-type sample. The maximum open circuit photovoltage and the maximum energy conversion efficiency are 0.59 V and 6.9% for n-type sample and are 0.69 V and 5.6% for p-type sample.