To provide a surface temperature measurement device and method that enable precise measurement of the surface temperature of a workpiece such as steel (wheel, steel pipe, steel plate, rail, or the like) that is being water-cooled. This surface temperature measurement device (100) is provided with: a radiation thermometer (1) for detecting heat radiation light radiated from the surface of a workpiece (W) that is being water-cooled; a housing (2) which opens on a workpiece (W) side and which internally accommodates at least the light-receiving unit (11) part of the radiation thermometer (1); and an optical glass (3) that is tightly fitted inside the housing (2) between the workpiece (W) and the light-receiving unit (11) of the radiation thermometer (1) as part of the radiation thermometer (1), and allows the heat radiation light to pass through. The end surface of the optical glass (3) on the workpiece (W) side is arranged close to the surface of the workpiece (W).