A fuel tank manufacturing apparatus for a fuel tank, the fuel tank having therein a built-in component with a head portion, a neck portion, and a shoulder portion, and having the built-in component anchored to a tank body with a part of a parison wrapped around the neck portion during molding the tank body, includes: a pair of molding dies to have the parison transferred to the built-in component by blow molding; and shaping devices respectively provided in the pair of molding dies, wherein the shaping devices each include: an end surface to contact the parison; a recess provided in the end surface to receive the head portion and the neck portion and covered by the shoulder portion during molding; and an air hole provided in an area of a bottom surface of the recess corresponding to the head portion through which air pressure is applied toward the head portion.

A fuel tank manufacturing apparatus for a fuel tank, the fuel tank having therein a built-in component with a head portion, a neck portion, and a shoulder portion, and having the built-in component anchored to a tank body with a part of a parison wrapped around the neck portion during molding the tank body, includes: a pair of molding dies to have the parison transferred to the built-in component by blow molding; and shaping devices respectively provided in the pair of molding dies, wherein the shaping devices each include: an end surface to contact the parison; a recess provided in the end surface to receive the head portion and the neck portion and covered by the shoulder portion during molding; and an air hole provided in an area of a bottom surface of the recess corresponding to the head portion through which air pressure is applied toward the head portion.