Provided are an etching method capable of improving an etching factor, and a method of manufacturing a circuit device using the etching method. In the etching method, an etching resist is firstly coated on a surface of a conductive foil as an etching target material. Then, the etching resist is subjected to selective exposure by use of an exposure mask, thereby selectively transforming the etching resist. In this way, a non-exposed region is formed as a remaining region having a cross section, in which a lower part thereof is greater than an upper part thereof. Thereafter, the etching resist in a region other than the remaining region is removed by use of a solution, and the conductive foil is subjected to etching by use of the remaining region as a mask.