To provide a heat transmission structure by which heat generating from a semiconductor can be instantaneously dissipated in a piezoelectric oscillator as an electronic part covering resin, in a cavity when a semiconductor is molded in a container having the cavity to house a semiconductor 37 to be mounted by flip chip.

The piezoelectric oscillator as an electronic part is made by filling a cavity 20 with a first resin 38 and a second resin 39 covering the first resin 38, when a semiconductor 37 is molded in a container 1 having the cavity 20 to house the semiconductor 37 to be mounted by flip chip. In this case, the semiconductor 37 is surrounded by the first resin 38, and the first resin 38 is covered with the second resin 39. Then, an electrode film 6 formed by metallization is arranged on the entire surface of the inner wall of the cavity 20 that is formed in such the manner.