To obtain an oscillator by which a wide variable frequency band width and sufficient frequency precision are simultaneously obtained and also which is easily controlled by providing plural input terminals for inputting the control signal of the frequency of an output signal.

The plural input terminals 7 and 8 are provided for inputting the control signal of the frequency of the output signal. In the oscillator, a transistor 2 is oscillated, the frequency of the signal to be outputted from a signal output terminal 9 is value-decided by a crystal vibrator 3 on the whole but an oscillation frequency is controlled from an external part by changing the capacitance of variable capacitance diodes 4 and 5 in accordance with voltages inputted from the input terminals 7 and 8. At this time, the sensitivity of the variable width of the frequency in the output signal as against the change width of the voltages to be inputted from the input terminals 7 and 8 is made different in the input terminal 7 and the input terminal 8 is not increased to extend the variable width of the frequency at the same resolution without increasing the number of bits in a D/A converter for deciding an inputted control signal voltage.