In a method for producing an electronic component device, a heat bonding step is performed in a state in which low melting point metal layers including low melting point metals including, for example, Sn as the main component, are arranged to sandwich, in the thickness direction, a high melting point metal layer including a high melting point metal including, for example, Cu as the main component, which is the same or substantially the same as high melting point metals defining first and second conductor films to be bonded. In order to generate an intermetallic compound of the high melting point metal and the low melting point metal, the distance in which the high melting point metal is to be diffused in each of the low melting point metal layers is reduced. Thus, the time required for the diffusion is reduced, and the time required for the bonding is reduced.