A method of manufacturing a shell type needle roller bearing including a shell outer ring having an inner circumferential raceway surface and a pair of inward flange portions (11b, 11c) in both end portions of the shell outer ring; a plurality of needles that are disposed in the shell outer ring in such a way as to be capable of rolling along the raceway surface of the shell outer ring; and a retainer having a plurality of pockets for retaining the plurality of needles, wherein the diameter of the retainer can be reduced, wherein after both the flange portions (11b, 11c) of the shell outer ring are formed and a heat treatment is applied to the shell outer ring, the diameter of the retainer having the plurality of needles assembled therewith is reduced to a diameter smaller than a flange-portion inner diameter of the shell outer ring and the retainer is inserted into the shell outer ring using a retainer insertion jig, wherein the retainer insertion jig is formed of a female jig and a male jig, wherein a shell outer ring-mounting stepped portion, in which the shell outer ring can be mounted, is provided at one axial end of the female jig, has a diameter greater than the outer diameter of the shell outer ring, and is axially concave, wherein a retainer-mounting stepped portion, in which the retainer can be mounted while being assembled with the plurality of needles, is provided at the other axial end of the female jig, is coaxial with the shell outer ring-mounting stepped portion, has a diameter greater than the maximum outer diameter of the retainer with which the plurality of needles are assembled, and is axially concave, wherein a small-diameter hole is provided on an inside end surface of the shell outer ring-mounting stepped portion, is coaxial with the shell outer ring-mounting stepped portion, and has a diameter smaller than the flange-portion inner diameter of the shell outer ring, wherein the small-diameter hole is gradually connected to the retainer-mounting stepped portion via a reduced diameter hole with a tapered shape, the diameter of which increases from the small-diameter hole toward the retainer-mounting stepped portion, wherein the male jig includes a body portion which has a diameter smaller than that of the small-diameter hole of the female jig such that the body portion can be inserted into the small-diameter hole, and a retainer mounting portion that is coaxial with the body portion, protrudes in an axial direction while being adjacent to the body portion, and has a diameter that is smaller than a diameter obtained by subtracting two times the outer diameter of the needle from the diameter of the small-diameter hole, wherein a stepped portion between the body portion and the retainer mounting portion serves as a retainer pressing portion that is a flat surface perpendicular to the axis, and wherein when the retainer is inserted into the shell outer ring, the shell outer ring is mounted in the shell outer ring-mounting stepped portion of the female jig, the retainer having the plurality of needles assembled therewith is mounted in the retainer mounting portion of the male jig, or in the retainer-mounting stepped portion of the female jig, and the male jig is inserted into the female jig from the retainer-mounting stepped portion side of the female jig, and thus the retainer having the plurality of needles assembled therewith is inserted into the shell outer ring.