A surface acoustic wave oscillator includes: a cross-coupled circuit including first and second active elements differentially connected to first and second output terminals; first and second surface acoustic wave elements having different resonance frequencies and connected to the cross-coupled circuit in parallel; a first variable capacitance circuit including a first variable capacitance element and changing the resonance frequency of the first surface acoustic wave element; and a second variable capacitance circuit including a second variable capacitance element and changing the resonance frequency of the second surface acoustic wave element, wherein the first surface acoustic wave element is connected to the first variable capacitance circuit, the second surface acoustic wave element is connected to the second variable capacitance circuit, and oscillating outputs from combining outputs of the first and second surface acoustic wave elements are outputted by the cross-coupled circuit.