To miniaturize and thin a device and to reduce cost by arranging a piezoelectric oscillator in a groove part held by mounting faces where a semiconductor integrated circuit is flip chip-bonded.

An electrode pattern 3 for connecting it to a semiconductor integrated circuit for real time clock (IC chip) 2 is metallized by a base 1 formed by the insulated substrate of stack ceramic with a metal wiring material by printing. Metallic bumps 4 are formed on the electrode pads of an IC chip 2 and they are connected with the electrode patterns 3 formed on the base 1 by flip chip bonding technology. A tuning fork-type crystal oscillator 6 has two micro opening parts 8 provided for the supporting part 7. The opening parts 8 and the bumps 4 provided for the electrode pads 9a and 9b for crystal oscillator connection of the IC chip 2 are connected and fixed by conductive adhesive 5. Thus, the crystal oscillator 6 is stored in the groove part 11 of the base 1 by mounting the IC chip 2 so that it is connected to the respective electrode patterns 3 formed on the surface 10 of the base 1.