Ultrasonic testing device, method, program, and ultrasonic testing system

An ultrasonic testing device comprising:

• a signal acquisition unit that receives a test object reflected echo signal relating to a reflected echo from an ultrasonic probe, which irradiates an inside of a test object with an ultrasonic wave and receives the test object reflected echo from the test object;
• a defect detection unit that detects a defect of the test object based on the test object reflected echo signal;
• and
• a display unit that displays a detection result of the defect detection unit,
• wherein the defect detection unit detects, as a first measured value, a maximum amplitude value of the test object reflected echo signal beyond a first threshold value by comparing a signal strength of the test object reflected echo signal with the first threshold value in an evaluation range between a first position at a first distance from a surface of the test object and a bottom surface of the test object, and detects the defect of the test object by comparing the first measured value with a first reference value,
• the first threshold value is a value smaller than a maximum amplitude value of a surface reflected echo signal of a normal test object, and
• the first reference value is a value larger than the first threshold value, and in an evaluation range for the normal test object, the first reference value is a maximum amplitude value of a reference reflected echo signal of the normal test object beyond the first threshold value, by comparison of a signal strength of the reference reflected echo signal of the normal test object with the first threshold value, wherein the reference reflected echo signal is obtained within the evaluation range for the normal test object.