An activate signal generating circuit, to which a first and a second activate signals which are pulse signals are applied, and which generates an internal activate signal, has a first delay element. The internal activate signal is activated based on timings of front (active transient) edges of the first and second activate signals. When a timing of a rear (inactive transient) edge of the first activate signal is earlier than a timing of a rear edge of the second activate signal, the internal activate signal goes inactivate based on the timing of the rear edge of the first activate signal, and when the timing of the rear edge of the first activate signal is later than the timing of the rear edge of the second activate signal, the internal activate signal goes inactivate after a predetermined delay time based on a delay time of the first delay element.