To provide an inexpensive thermally-actuated steam trap that has a simple structure and can measure the surface temperature of a trap itself.

A thermo-label 2 is affixed to a surface of a name plate 1 to be attached to an outer surface of a thermally-actuated steam trap. The thermo-label 2 indicates whether the temperature of the name plate 1 part is in a normal-temperature state of, for example, around 20°C, or in a high-temperature state of around 100°C by the fact that built-in thermo indicating parts 3, 4, 5 are successively discolored, for example, from blue to red according to the temperature of the name plate 1. By the visual check of the thermo indicating state of the thermo-label 2 by a checker, it can be instantaneously determined in situ whether the temperature of the outer surface of the trap is high or low, preventing the checker from touching the trap and getting burned thereby.