A probe-holding apparatus for a probe for checking steam generator tubes, said apparatus comprising a telescopic arm resiliently urged towards its position of maximum extension and said arm having first and second opposed ends, a support, first ball-joint means movably mounting the first end of the arm on the support, a carriage, and second ball-joint means mounting said carriage on said second end of said arm, said carriage comprising an endless belt formed with projections spaced apart in accordance with spacing of said tubes, guide means for a probe, and a stepping motor for driving said belt, the guide means for the probe and the projections being disposed in the same direction.