To provide an echo canceller capable of more quickening adaptation of a filter coefficient for an initial lock period while suppressing cost increase.

The echo canceller performs an arithmetic operation of the filter coefficient ω(n) of an adaptive filter by selecting a method of increasing an adaptation speed up to the initial lock period and performs the arithmetic operation by selecting a method of improving adaptation accuracy after a lapse of the initial lock period. Concretely, the echo canceller replaces a learning coefficient μ being an arithmetic parameter of the filter coefficient ω(n) with a prescribed value f for the initial lock period (steps S1 to S4) and carries out the arithmetic operation on the basis of Equation (3) after a lapse of the initial lock period (steps S5 to S8).