Abstract: An internal meshing type gear device includes: an internal gear; and an external gear that meshes with the internal gear, in which, when a straight line passing through an external gear center and an internal gear center is defined as a gear center line, a pitch point between the external gear and the internal gear is positioned radially inside an external tooth tip circle and an internal tooth tip circle, an intersection point between a normal line to a contact point locus between the external gear and the internal gear and the gear center line is positioned between the pitch point and the external gear center, and the contact point locus is positioned in a meshing region between the external and internal tooth tip circles within an angle range in which an angle centered on the pitch point from the gear center line is 0 to ?/2 [rad].