An ADC (12) in an optical receiver (1) generates a sample signal composed of time series samples by oversampling a received signal that is an electrical signal converted from an optical signal by a light receiving unit (11). A symbol timing detection unit (132) of a DSP unit (13) detects a symbol timing in the sample signal. When it is determined that a symbol timing is appearing at a longer interval than a predetermined interval based on this detection result, a symbol timing adjusting unit (133) skips one or more samples included in the sample signal to read out samples at the predetermined interval, while when it is determined that the symbol timing is appearing at a shorter interval than the predetermined interval, the symbol timing adjusting unit inserts the same samples as one or more samples included in the sample signal immediately after the one or more samples to read out the samples at the predetermined interval.