An inventory of the mammals of Camiguin Island conducted in 1994 and 1995 documented the presence of a previously unknown species of Philippine forest mouse of the endemic Philippine genus Apomys, which is here named and described. Based on molecular data, the new species is most closely related to two species (A. hylocoetes and A. insignis) from Mindanao Island and to an unnamed species from Leyte, Biliran, and Bohol islands. The new species is diagnosed in comparison to its three closest relatives on the basis of slightly browner and less russet fur, slightly greater size overall, a moderately long and broad hind foot with small plantar pads, large tail scales, slightly narrower zygomatic width and mastoid breadth, deep rostrum of moderate length, a long orbit and braincase, narrow palate, large incisive foramina, short distance from the posterior edge of the incisive foramina to the anterior edge of the first upper molar, bony palate that extends well to the posterior of the posterior edge of the last upper molar, bullae that are more strongly oriented toward the cranial midline axis, third upper molar without a conspicuous anterolabial cusp, and a number of more subtle features. It is one of two species of mammals now known to be endemic to Camiguin, the other being Bullimus gamay (Rickart et al., 2002). Both are common in rain forest on Camiguin Island at upper elevations. The presence of two endemic mammals on this small (265 km²) island is remarkable; there are no smaller islands in the Philippines known to support endemic mammal species.