A gear transmission is provided with an internal gear and an external gear that eccentrically rotates relative to the internal gear while meshing with internal gear. The internal gear includes first recesses formed on an inner circumferential surface of a case so as to be side-by-side in a circumferential direction, and inner pins inserted into the first recesses. A second recess is formed on the inner circumferential surface of the case within a distance from the center of a first recess along the circumferential direction that equals the tooth pitch of the external gear. Lubricant is retained in the second recess.