The shielding portion 6 covers a part of a lower surface 40 of the graphite sheet 4, which is a surface on a circuit board 8 side not in contact with the heat conductive portion 5. The shielding portion 6 is made of a material having an insulating property. The shielding portion 6 is made of, for example, a resin material. The lower surface 40 of the graphite sheet 4 includes a contact surface 40a in contact with the heat conductive portion 5 and a shielded surface 40b around the contact surface 40a. The lower surface 40 is included in a circuit-board side surface of the graphite sheet 4. The shielded surface 40b is a portion that is not in contact with (i.e., is not covered by) the heat conductive portion 5 and is a portion that overlaps the shielding portion 6 located below in the vertical direction. The shielding portion 6 is provided at a position separated downward from the shielded surface 40b. As shown in FIG. 6, an outer periphery portion 64 of the shielding portion 6 is located outside an outer periphery portion 41 of the graphite sheet 4. The shielding portion 6 covers the entire lower surface 40 of the graphite sheet 4 outside the contact surface 40a.