A receiver includes: a correlation value calculation unit calculating a first cross-correlation function between a received signal, having a preamble spread with an up chirp and a down chirp, and the up chirp and calculating a second cross-correlation function between the received signal and the down chirp; a power value calculation unit calculating first and second power values of the first and second cross-correlation functions; a correlation power memory storing the first and second power values at each sample timing for one period of a spread code; a threshold determination unit determining first and second estimated timings from the first and second power values for one period of the spread code, respectively; and an estimation unit estimating a spread code timing of a transmitter using the first and second estimated timings, and performing coarse estimation of a frequency offset with respect to the transmitter.