A method for manufacture of a housing part provided with a ventilation filter, comprising: a step of disposing a ventilation filter part (19, 191, 192, 193, 194, 195) including a support body (27, 30, 37, 47, 60) and a ventilation filter (25, 26, 56) fixed to the support body (27, 30, 37, 47, 60) in a forming die at a predetermined position and clamping the forming die; and a step of injecting resin into a cavity defined within the forming die as a result of clamping to make the resin and the ventilation filter part (19, 191, 192, 193, 194, 195) into one piece and thereby molding a housing part formed of the ventilation filter part and the resin, wherein the ventilation filter (25, 26, 56) is in a form of a membrane and the support body (27, 30, 37, 47, 60) is in a form of a frame that fixes the ventilation filter by sandwiching a peripheral portion (25k, 26k, 56k) thereof from above and below; characterized in that: the forming die includes a movable die and a stationary die; the movable die has a protruding pin; the stationary die is provided with a gate; the stationary die is provided with a concave portion (44c 45c) in which the ventilation filter part (19, 191, 192, 193, 194, 195) is fit for positioning; in the step, the ventilation filter part (19, 191, 192, 193, 194, 195) is fit in the concave portion (44c 45c), and the forming die is clamped in such a manner that clearances are defined above and below the ventilation filter (25, 26, 56) and that the forming die comes into close contact with top, bottom and part of side faces (27p, 27q, 27r, 47r) of the support body (27, 30, 37, 47, 60) so as to prevent the resin from flowing into the clearances; and in the step, the support body (27, 30, 37, 47, 60) is made integral with the resin only at part of the side face (27r, 47r) of the support body (27, 30, 37, 47, 60), the part of the side face (27r,47r) protruding from the concave portion (44c, 45c) and facing the cavity. a step of disposing a ventilation filter part (19, 191, 192, 193, 194, 195) including a support body (27, 30, 37, 47, 60) and a ventilation filter (25, 26, 56) fixed to the support body (27, 30, 37, 47, 60) in a forming die at a predetermined position and clamping the forming die; and a step of injecting resin into a cavity defined within the forming die as a result of clamping to make the resin and the ventilation filter part (19, 191, 192, 193, 194, 195) into one piece and thereby molding a housing part formed of the ventilation filter part and the resin, wherein the ventilation filter (25, 26, 56) is in a form of a membrane and the support body (27, 30, 37, 47, 60) is in a form of a frame that fixes the ventilation filter by sandwiching a peripheral portion (25k, 26k, 56k) thereof from above and below; characterized in that: the forming die includes a movable die and a stationary die; the movable die has a protruding pin; the stationary die is provided with a gate; the stationary die is provided with a concave portion (44c 45c) in which the ventilation filter part (19, 191, 192, 193, 194, 195) is fit for positioning; in the step, the ventilation filter part (19, 191, 192, 193, 194, 195) is fit in the concave portion (44c 45c), and the forming die is clamped in such a manner that clearances are defined above and below the ventilation filter (25, 26, 56) and that the forming die comes into close contact with top, bottom and part of side faces (27p, 27q, 27r, 47r) of the support body (27, 30, 37, 47, 60) so as to prevent the resin from flowing into the clearances; and in the step, the support body (27, 30, 37, 47, 60) is made integral with the resin only at part of the side face (27r, 47r) of the support body (27, 30, 37, 47, 60), the part of the side face (27r,47r) protruding from the concave portion (44c, 45c) and facing the cavity. the forming die includes a movable die and a stationary die; the movable die has a protruding pin; the stationary die is provided with a gate; the stationary die is provided with a concave portion (44c 45c) in which the ventilation filter part (19, 191, 192, 193, 194, 195) is fit for positioning; in the step, the ventilation filter part (19, 191, 192, 193, 194, 195) is fit in the concave portion (44c 45c), and the forming die is clamped in such a manner that clearances are defined above and below the ventilation filter (25, 26, 56) and that the forming die comes into close contact with top, bottom and part of side faces (27p, 27q, 27r, 47r) of the support body (27, 30, 37, 47, 60) so as to prevent the resin from flowing into the clearances; and in the step, the support body (27, 30, 37, 47, 60) is made integral with the resin only at part of the side face (27r, 47r) of the support body (27, 30, 37, 47, 60), the part of the side face (27r,47r) protruding from the concave portion (44c, 45c) and facing the cavity.