A method of manufacturing a housing structure that includes an electronic unit including a first circuit portion and a second circuit portion protruding from the first circuit portion, and a housing in which the electronic unit is housed, the electronic unit and the housing being integral with each other, the method comprising: preparing a mold for insert molding in which the electronic unit is housed, the mold including an upper wall surface facing an upper surface of the second circuit portion and side wall surfaces facing side surfaces of the second circuit portion; placing the electronic unit in the mold; and injecting the resin into the mold in which the electronic unit has been placed, wherein the mold includes: a first chamber in which the first circuit portion of the electronic unit is housed; a second chamber in which the second circuit portion of the electronic unit is housed, the second chamber being communicated with the first chamber; and a gate through which the resin is injected into the first chamber, and the resin injected into the first chamber through the gate flows into the second chamber from an upper portion of the second circuit portion, characterized in that the mold is configured such that a flow resistance of a resin flowing through a space between each of the side surfaces of the second circuit portion and the corresponding side wall surface is lower than a flow resistance of the resin flowing through a space between the upper surface of the second circuit portion and the upper wall surface; the second circuit portion is supported, as a cantilever portion, by the first circuit portion, and the second circuit portion is not in contact with an inner wall surface of the mold in a state where the electronic unit is placed in the mold. preparing a mold for insert molding in which the electronic unit is housed, the mold including an upper wall surface facing an upper surface of the second circuit portion and side wall surfaces facing side surfaces of the second circuit portion; placing the electronic unit in the mold; and injecting the resin into the mold in which the electronic unit has been placed, wherein the mold includes: a first chamber in which the first circuit portion of the electronic unit is housed; a second chamber in which the second circuit portion of the electronic unit is housed, the second chamber being communicated with the first chamber; and a gate through which the resin is injected into the first chamber, and a first chamber in which the first circuit portion of the electronic unit is housed; a second chamber in which the second circuit portion of the electronic unit is housed, the second chamber being communicated with the first chamber; and a gate through which the resin is injected into the first chamber, and the resin injected into the first chamber through the gate flows into the second chamber from an upper portion of the second circuit portion, characterized in that the mold is configured such that a flow resistance of a resin flowing through a space between each of the side surfaces of the second circuit portion and the corresponding side wall surface is lower than a flow resistance of the resin flowing through a space between the upper surface of the second circuit portion and the upper wall surface; the second circuit portion is supported, as a cantilever portion, by the first circuit portion, and the second circuit portion is not in contact with an inner wall surface of the mold in a state where the electronic unit is placed in the mold.