According to embodiments, an ultrasonic inspection apparatus comprises: an ultrasonic array probe having a plurality of ultrasonic elements; an estimated shape reflected wave arrival time calculator for computing the estimated shape reflected wave arrival time for the estimated shape reflected wave on the basis of the estimated sound velocity in the test object; an actual shape reflected wave arrival time extractor for extracting the actual shape reflected wave arrival time on the basis of the actual shape reflected wave; a shape reflected waves time difference calculator for computing the difference by subtracting the actual shape reflected wave arrival time from the estimated shape reflected wave arrival time as shape reflected waves time difference; and a delay time calculator for computing the delay times for mutually shifting the timings of ultrasonic wave transmission and ultrasonic wave reception by the ultrasonic elements, considering the shape reflected waves time differences.