To provide a mobile automatic penetration tester which has a low height, compact size and can be carried even by a light van, moreover, this mobile tester can be easily carried to the job site, pullout of a penetrated rod can be performed at the same time and thus the workability can be greatly improved for this automatic penetration tester.

This tester comprises a mobile crawler 1, a supporting base 5 installed at the upper portion of the crawler, an expandable guide rail 20 erected on the supporting base 5, a lifting frame 12 lifted and lowered by guiding by the rail, a weight 16 attached to the lifting frame 12, a hydraulic cylinder 21 which is erected on the supporting base 5 with the cylinder rod 21A directed upward and its tip contacts to and separates from the lifting frame 12, a rod penetration chuck 14 holding the penetration rod to be penetrated underground, a drive mechanism rotating the rod penetrating chuck 14, and a rod pullout chuck 15 provided on the same shaft with the chuck 14 for the rod penetration.