PURPOSE: To reduce the power consumption of the entire circuit and to make the size small by using a high speed switching circuit so as to select any of plural SAW elements and using the selected SAW element thereby oscillating the oscillating element.

CONSTITUTION: The SAW circuit 2 consists of an RF switch driver circuit 16, RF switch circuits 17, 18 connecting one common terminal and any of plural selection terminals based on an output of the circuit 16 and SAW resonance circuits 19a-19n connecting respectively between the selection terminals of the switch circuits 17, 18 and whose plural resonance frequencies are set differently. Then based on a selection signal supplied from a switch circuit 3, one of the SAW resonance circuits 19a-19n is selected and a collector and a base of a transistor(TR) 14 are connected by the selected SAW resonance circuit to oscillate the TR 14. Thus, the power consumption of the entire circuit is reduced and the size is made small.