In a heat treatment method for obtaining a bearing ring for an annular roller bearing whose thickness changes in an axial direction, the heat treatment method includes (A) applying a quenching process to a work which is annular, made of high carbon chromium bearing steel, and having a thickness changing in an axial direction, (B) applying a tempering process to the work which is quenched to entirely soak the work in cooling liquid and inductively heat the work in a state that the work is soaked in the cooling liquid, and (C) applying a finishing process to the work which is tempered.