A method of manufacturing a resin sealing module including a substrate mounted with electronic components (2, 3), a module case housing the substrate, and a cured sealing resin filling the module case and sealing the substrate, the method of manufacturing the resin sealing module comprising: a mounting step of mounting the electronic components (2, 3) on a mounting surface of the substrate; a housing step of housing the substrate with the electronic components (2, 3) in the module case; an injection step of injecting an uncured liquid sealing resin into the module case; a positioning step of positioning a mold member (20, 40, 70, 80) having a main plate portion in a plate shape and a first partition wall (22, 72) formed in a cylindrical shape on the main plate portion, so that the first partition wall (22, 72) faces the mounting surface, the first partition wall (22, 72) protruding from a first main surface of the main plate portion and having an inside space, and immersing a protruding end portion (22a, 72a, 82a) of the first partition wall (22, 72) into the uncured liquid sealing resin while holding a gas layer in the inside space of the first partition wall (22, 72), so that a partial region (4A1) of an upper surface of the uncured liquid sealing resin is depressed by the gas layer; a curing step of curing the uncured liquid sealing resin in the module case to form the cured sealing resin; and a removal step of removing the mold member (20, 40, 70, 80) from the cured sealing resin, wherein the upper surface of the cured sealing resin has a recessed portion formed by the first partition wall (22, 72) and the gas layer depressing the upper surface of the uncured liquid sealing resin in the immersing step; a molded protruding portion is formed in the positioning step along an inner surface of the first partition wall and having an annular shape in plan view on a bottom surface of the recessed portion, the bottom surface of the recessed portion has a region inside the molded protruding portion and a region outside the molded protruding portion, and the region inside the molded protruding portion has a smaller surface roughness than that of the region outside the molded protruding portion. a mounting step of mounting the electronic components (2, 3) on a mounting surface of the substrate; a housing step of housing the substrate with the electronic components (2, 3) in the module case; an injection step of injecting an uncured liquid sealing resin into the module case; a positioning step of positioning a mold member (20, 40, 70, 80) having a main plate portion in a plate shape and a first partition wall (22, 72) formed in a cylindrical shape on the main plate portion, so that the first partition wall (22, 72) faces the mounting surface, the first partition wall (22, 72) protruding from a first main surface of the main plate portion and having an inside space, and immersing a protruding end portion (22a, 72a, 82a) of the first partition wall (22, 72) into the uncured liquid sealing resin while holding a gas layer in the inside space of the first partition wall (22, 72), so that a partial region (4A1) of an upper surface of the uncured liquid sealing resin is depressed by the gas layer; positioning a mold member (20, 40, 70, 80) having a main plate portion in a plate shape and a first partition wall (22, 72) formed in a cylindrical shape on the main plate portion, so that the first partition wall (22, 72) faces the mounting surface, the first partition wall (22, 72) protruding from a first main surface of the main plate portion and having an inside space, and immersing a protruding end portion (22a, 72a, 82a) of the first partition wall (22, 72) into the uncured liquid sealing resin while holding a gas layer in the inside space of the first partition wall (22, 72), so that a partial region (4A1) of an upper surface of the uncured liquid sealing resin is depressed by the gas layer; a curing step of curing the uncured liquid sealing resin in the module case to form the cured sealing resin; and a removal step of removing the mold member (20, 40, 70, 80) from the cured sealing resin, wherein the upper surface of the cured sealing resin has a recessed portion formed by the first partition wall (22, 72) and the gas layer depressing the upper surface of the uncured liquid sealing resin in the immersing step; a molded protruding portion is formed in the positioning step along an inner surface of the first partition wall and having an annular shape in plan view on a bottom surface of the recessed portion, the bottom surface of the recessed portion has a region inside the molded protruding portion and a region outside the molded protruding portion, and the region inside the molded protruding portion has a smaller surface roughness than that of the region outside the molded protruding portion.