A pin terminal for a glow plug comprising: a small-diameter portion (10a, 33a) which has a shaft shape extending in an axial direction and is to be connected to a conductive member for supplying electric power from an outside; a flange that is formed integrally with a front end of the small-diameter portion (10a, 33a) and is formed so as to have an outer diameter larger than an outer diameter of the small-diameter portion (10a, 33a); a cylindrical large-diameter portion (10b, 33b) that is formed integrally with a front end of the flange so as to be shorter than the small-diameter portion (10a, 33a) in the axial direction, is formed so as to have an outer diameter larger than the outer diameter of the small-diameter portion (10a, 33a) and smaller than the outer diameter of the flange, and includes a fitting recess formed therein in a radial direction so as to be recessed toward a rear end of the large-diameter portion (10b, 33b) from a front end of the large-diameter portion (10b, 33b) in the axial direction; and a engagement portion which is positioned between a maximum diameter position of the flange and the large-diameter portion (10b, 33b) and has an outer diameter gradually reduced toward the large-diameter portion (10b, 33b), wherein the large-diameter portion (10b, 33b) includes a crimp formation region which is formed in a range from a front end of the large-diameter portion to a front end of the engagement portion so as to have an even outer diameter and be capable of being crimped, characterized in that the flange includes a convex curved surface, said convex curved surface, when taken in cross-section in a direction perpendicular to the axial direction having a circular shape, wherein a step is formed on the convex curved surface at a side of the large-diameter portion (10b, 22b) with respect to the maximum diameter position. a small-diameter portion (10a, 33a) which has a shaft shape extending in an axial direction and is to be connected to a conductive member for supplying electric power from an outside; a flange that is formed integrally with a front end of the small-diameter portion (10a, 33a) and is formed so as to have an outer diameter larger than an outer diameter of the small-diameter portion (10a, 33a); a cylindrical large-diameter portion (10b, 33b) that is formed integrally with a front end of the flange so as to be shorter than the small-diameter portion (10a, 33a) in the axial direction, is formed so as to have an outer diameter larger than the outer diameter of the small-diameter portion (10a, 33a) and smaller than the outer diameter of the flange, and includes a fitting recess formed therein in a radial direction so as to be recessed toward a rear end of the large-diameter portion (10b, 33b) from a front end of the large-diameter portion (10b, 33b) in the axial direction; and a engagement portion which is positioned between a maximum diameter position of the flange and the large-diameter portion (10b, 33b) and has an outer diameter gradually reduced toward the large-diameter portion (10b, 33b), wherein the large-diameter portion (10b, 33b) includes a crimp formation region which is formed in a range from a front end of the large-diameter portion to a front end of the engagement portion so as to have an even outer diameter and be capable of being crimped, characterized in that the flange includes a convex curved surface, said convex curved surface, when taken in cross-section in a direction perpendicular to the axial direction having a circular shape, wherein a step is formed on the convex curved surface at a side of the large-diameter portion (10b, 22b) with respect to the maximum diameter position.