Abstract: A device for the non-destructive testing of rolled steel plate and the like for the presence of internal flaws or defects such as non-metallic inclusions, inhomogeneities and the like, comprising a carriage adapted to be traversed in relation to the surface of the plate to be tested and parallel thereto, said carriage having attached thereto, through the medium of connecting links, at least one ultrasonic test head including an ultrasonic transmitter and an ultrasonic receiver supported by a test head holder and adapted to be tilted about two mutually perpendicular tilting axes extending substantially parallel to the surface of the plate to be tested, said connecting links being adapted to raise and lower said test head holders individually and comprising for each test head holder both an elevating cylinder and separate guide means adapted positively to guide said test head holder in a direction extending at right angles to the raising and lowering direction, said elevating cylinder and said guide means being