To prevent generation differentiation of a surface step height of a thermal insulation panel by chips generated when boring an anchor hole on a wall surface.

In this thermal insulation panel 10, a reverse surface is composed of a thermal insulation board 11, and a front face is composed of a surface plate 12. A recessed part 14 is formed in a crossing part of the reverse surface of this thermal insulation board 11 and an upper side edge surface of the thermal insulation board 11. When boring a hole by a drill by applying a back face of the upper stage side thermal insulation panel 10 to a wall surface of an existing wall 21, the generated chips P are stored in the recessed part 14 arranged on the edge surface of the thermal insulation panel 10. Thus, the upper stage side thermal insulation panel 10 is not pushed forward, and the surface step height is not differentiated between the mutual upper-lower thermal insulation panels 10.