A method for producing a resin molding die (13) for molding a first substrate (2) having a flow path (2b) and a through-hole (2a), wherein a base die (10) having a concave part (10b) corresponding to the flow path (2b) and a through-hole (10a) corresponding to through-hole (2a) and deeper than the concave part (10b) is prepared, the base die (10) is subjected to electroforming with a first material and is then subjected to electroforming with a second material which is different from the first material, and a protruding part for forming through-hole (10a) by removing the first material that was electrodeposited on through-hole (10a) is formed. The first material has a smaller electroforming stress than the second material, the first material exerts a higher adhesiveness with regard to the base die than the second material, and the second material is harder than the first material.