To improve power resistance by inserting a core material between an outer skin and an inner skin and making a tip of the core material exposed to concentrated antenna transmission power with a material with excellent thermal conductivity.

In the radome 2 provided around the outer side of a transmission antenna 1 and whose core material 5 is inserted between an outer skin 4 and an inner skin 3, a tip of the core material onto which transmission power of the antenna 1 is concentrated is made of the core material 6 with excellent thermal conductivity. When a radio wave sent from the transmission antenna 1 passes through an inner skin material 3 of the radome 2, the core material 5, the core material 6 with excellent thermal conductivity and an outer skin material 4, each radome component material is heated. The heat generated at the tip of the inner skin material 3 is delivered to the outer skin material 4 while a heat generation area is expanded by the core material 6 with excellent thermal conductivity and cooled by natural convection or the like with the heat generated in the outer skin material.