A strut type shock absorber (1) comprises an outer shell (2) and a knuckle bracket (3). A curved portion (4) of the knuckle bracket (3) positioned in close contact with the outer shell (2) comprises a reinforcing flange (7) formed by bending a part of an axial end of the curved portion (4) outward and a no-flange portion (6), both of which are welded onto the outer shell (2). By setting an axial distance (H) from an inflection start point to an inflection end point of the outer circumferential surface of the reinforcing flange (7) to be equal to an axial distance from the inflection start point to the no-flange portion (6), and by forming an insulation portion (9) between the reinforcing flange (7) and the no-flange portion (6), an effectual welding operation and the prevention of molten metal from flowing over the reinforcing flange (7) during welding are realized.