A method of manufacturing a plasmon generator includes the steps of: forming an etching mask on a dielectric layer; forming an accommodation part by etching the dielectric layer using the etching mask; and forming the plasmon generator to be accommodated in the accommodation part. The step of forming the etching mask includes the steps of: forming a patterned layer on an etching mask material layer, the patterned layer having a first opening that has a sidewall; forming a structure by forming an adhesion film on the sidewall, the structure having a second opening smaller than the first opening; and etching a portion of the etching mask material layer exposed from the second opening.