The first report stated that the nylon gear was available for use in power transmission. But nylon gear has a problem of abrasion. In this paper, confirming this abrasion, is investigated the dependency of abrasion on load and sliding velocity of tooth in nylon gear for power transmission which meshes with steel gear. It has been confirmed that the phenomenon like a creep occurs on a tooth of power transmission nylon gear. And it has been investigated how this phenomenon influences abrasion of nylon gears.