Abstract: Disclosed herein is an optical mouse. A body of the mouse has a bottom area sufficient to stand up independently and also has a pen shape to be wrapped around and gripped by the user's thumb and index finger. The pen shaped body is formed with a protruding portion having an inclined surface to allow the user's middle finger to rest thereon in a state wherein the user's thumb and index finger wrap around and grip the body and the middle finger is bent. The optical mouse causes no stress on the user's wrist in use by virtue of the pen shaped body, and has stability and accuracy by virtue of a bottom area thereof to allow the mouse to stand up independently, and can be easily assembled by using a standard optical lens, resulting in improved productivity and reduced production costs.