To provide a manufacturing method of a brake piston made of phenol resin with excellent rigidity, long term heat resistance, brake fluid resistance, or the like in high-temperature atmosphere by improving heat resistance without impairing various characteristics of conventional brake piston made of phenol resin.

The manufacturing method of a brake piston made of phenol resin is characterized by heat-treating at two steps of temperature after forming using phenolic resin molding material. Desirably, the heat treatment of the first step is carried out at the temperature of 160 to 190°C for 2 to 8 hours, and the heat treatment of the second step is carried out at the temperature of 200 to 240°C for 2 to 8 hours.