A method for manufacturing a terminal-equipped case member having an external terminal for electrically connecting an external device, which is fixed to a case body for housing an electronic component or a case member constituting a case lid that is attached to the case body, the terminal-equipped case member comprising: a base material made of metal that forms the case member; the external terminal made of metal that is inserted into a through hole formed through the base material; and a sealing member formed of a first resin material that seals a gap between the external terminal in the through hole and the base material, wherein the external terminal and the sealing member are bonded to each other through a terminal adhesion layer formed of a second resin material with a higher adhesion to the external terminal than that of the first resin material, the first resin material is an engineering plastic or a super engineering plastic, and the second resin material is an epoxy resin, a polyamide-imide resin, or a polyimide resin, the method comprising: a preparation step of preparing the base material having the through hole; a terminal adhesion layer formation step of forming the terminal adhesion layer on the external terminal; and a sealing step of sealing the gap by filling the gap between the external terminal in the through hole and the base material with the first resin material in a state that the external terminal is inserted into the through hole to form the sealing member so that the external terminal and the sealing member are bonded to each other through the terminal adhesion layer, wherein in the terminal adhesion layer formation step, the terminal adhesion layer is formed on the external terminal by electrodeposition. a base material made of metal that forms the case member; the external terminal made of metal that is inserted into a through hole formed through the base material; and a sealing member formed of a first resin material that seals a gap between the external terminal in the through hole and the base material, wherein the external terminal and the sealing member are bonded to each other through a terminal adhesion layer formed of a second resin material with a higher adhesion to the external terminal than that of the first resin material, the first resin material is an engineering plastic or a super engineering plastic, and the second resin material is an epoxy resin, a polyamide-imide resin, or a polyimide resin, the method comprising: a preparation step of preparing the base material having the through hole; a terminal adhesion layer formation step of forming the terminal adhesion layer on the external terminal; and a sealing step of sealing the gap by filling the gap between the external terminal in the through hole and the base material with the first resin material in a state that the external terminal is inserted into the through hole to form the sealing member so that the external terminal and the sealing member are bonded to each other through the terminal adhesion layer, a preparation step of preparing the base material having the through hole; a terminal adhesion layer formation step of forming the terminal adhesion layer on the external terminal; and a sealing step of sealing the gap by filling the gap between the external terminal in the through hole and the base material with the first resin material in a state that the external terminal is inserted into the through hole to form the sealing member so that the external terminal and the sealing member are bonded to each other through the terminal adhesion layer, wherein in the terminal adhesion layer formation step, the terminal adhesion layer is formed on the external terminal by electrodeposition.