A turbine blade maintenance method, the turbine blade including a first coating layer as a protective layer applied to an external surface and internal cooling flow channels for circulating a refrigerant, wherein the internal cooling flow channels open in a blade tip and a blade root of the turbine blade, the turbine blade maintenance method comprising: a first coating layer removing process where the first coating layer is removed by chemical treatment; a cleaning process where blast treatment for cleaning the turbine blade is performed after the first coating layer removing process; after the cleaning process, a blasted-particles cleaning process where ultrasonic cleaning treatment in which the turbine blade is immersed in a water basin and ultrasonic sound waves are conducted into the water basin to clean the turbine blade, and pressurized-water cleaning treatment in which pressurized water is sprayed into the internal cooling flow channels after performing the ultrasonic cleaning treatment are performed plural times; and a heat tinting process where heat treatment for testing whether the first coating layer remains on the turbine blade is performed after the blasted-particles cleaning process, wherein in the pressurized-water cleaning treatment, pressurized water is sprayed into the internal cooling flow channels from one of the openings in the blade tip and the openings in the blade root in a state where the turbine blade is supported in a support direction so that a longitudinal direction is along the vertical direction, the one of the openings being located on an upper side in a vertical direction, and in the blasted-particles cleaning process, after the support direction is switched so that upper and lower sides in the vertical direction of the turbine blade are inverted with respect to previous pressurized-water cleaning treatment, next pressurized-water cleaning treatment is performed. a first coating layer removing process where the first coating layer is removed by chemical treatment; a cleaning process where blast treatment for cleaning the turbine blade is performed after the first coating layer removing process; after the cleaning process, a blasted-particles cleaning process where ultrasonic cleaning treatment in which the turbine blade is immersed in a water basin and ultrasonic sound waves are conducted into the water basin to clean the turbine blade, and pressurized-water cleaning treatment in which pressurized water is sprayed into the internal cooling flow channels after performing the ultrasonic cleaning treatment are performed plural times; and a heat tinting process where heat treatment for testing whether the first coating layer remains on the turbine blade is performed after the blasted-particles cleaning process, wherein in the pressurized-water cleaning treatment, pressurized water is sprayed into the internal cooling flow channels from one of the openings in the blade tip and the openings in the blade root in a state where the turbine blade is supported in a support direction so that a longitudinal direction is along the vertical direction, the one of the openings being located on an upper side in a vertical direction, and in the blasted-particles cleaning process, after the support direction is switched so that upper and lower sides in the vertical direction of the turbine blade are inverted with respect to previous pressurized-water cleaning treatment, next pressurized-water cleaning treatment is performed.