To improve operational capability of temperature measurement and realize visual inspection even in a narrow part by remote control during removing thermal stress from heat conduction pipes in steam generator of reactor power equipment.

Inside the gap 9 of a guide 6 for a steam generator, whole temperature measuring tool 7 is inserted together with a rope 8. The whole tool 7 is provided with a wheel stage 12 having a wheel 14 at the lower part of two side plates 11 and a case 15 having a guide wheel 16 freely moving up and down at the upper part. On the wheel stage 12, a mirror 18 is fixed and a camera case 19 is above it so that the image in the mirror 18 is caught with a CCD camera. In the front of the camera case 19, a temperature measuring fiber 20 is fixed on a bracket 21 movable vertically. Temperature measurement is possible by drawing the rope 8 from outside of a hand hole 3, moving the whole tool 7, controlling up and down position of the temperature measuring fiber 20 and confirming the position with the mirror 18 and the CCD camera in the camera case 19, and setting in the specific position by remotely controlling.