Method for manufacturing an image pickup lens unit. In the second molding step, by performing additional molding with respect to a first holder member 20 in which a lens 10 has been inserted, the separation of the lens 10 can be prevented and, at the same time, a second holder member 30 welded to the first holder member 20 can be molded. Therefore, molding of the second holder member 30 and the process of joining the second holder member with the first holder member 20 can be performed together. Additionally, when the lens 10 is fixed from the side of a third molding portion 63 of a second mold 52, the lens 10 and the third molding portion 63 are brought in contact by an elastic biasing force, thereby reducing breakage or deformation of the lens 10.