An equalizer characteristics optimizing method includes acquiring a recovery clock timing from a reception signal; acquiring a predetermined sampling clock timing with respect to the recovery clock timing; latching the reception signal at the recovery clock timing; latching the reception signal at the sampling clock timing; comparing logic values obtained in the latching steps; collecting, after changing a characteristics setting of an equalizer, logic value comparison result data by repeating the recovery clock acquiring step, the acquiring of the sampling clock timing, the latching of the reception signal at the individual clock timings, and the comparing of the logic values, using the changed characteristics setting; and determining an optimum characteristics setting of an equalizer based on the collected logic value comparison result data.