A manufacturing method of a side view type light emitting device including a package body made of a synthetic resin material, the manufacturing method includes: providing an injection molding mold, for injection-molding the package body, including: a first mold provided with a first convex part for forming an upper surface side flat part on an upper surface of the package body; and a second mold provided with a first concave part for forming the upper surface side flat part; and fitting the first concave part around the first convex part so as to enter a liquid tight state with no space, injecting the synthetic resin material into each of the first and second molds so as to be filled therein, and hardening the synthetic resin material to form the package body in a state in which the first mold and the second mold are aligned with each other.