A method of manufacturing an electrically heated catalyst device includes preparation of a metal thin plate as a material of a metal electrode layer. The metal thin plate includes wiring portions, a base, a terminal portion, a second base, and a pseudo terminal portion. The method includes supplying current between the terminal portion and the pseudo terminal portion of the metal thin plate after fixing layers are formed; and forming the metal electrode layer by removing a portion of the metal thin plate between a smallest cross-sectional area portion and a distal end of the pseudo terminal portion through melting and cutting of the smallest cross-sectional area portion using the Joule heat generated by the supplied current. The smallest cross-sectional area portion is a part of the metal thin plate that has a smallest area in a cross section perpendicular to the extending direction of the wiring portions.