PROBLEM TO BE SOLVED: To provide a collapse prevention pipe for an excavated hole to be used suitably in a flat plate loading test method, the collapse prevention pipe being installed in a small installation space and curtailing time for setting up a test device.SOLUTION: A collapse prevention pipe 72s for an excavated hole is inserted into at least a part of a hole excavated into a ground, and forms a wall surface of the excavated hole 71. A loading test device includes a device body 2b having a fixing part to be frictionally fixed at a prescribed position in the excavated hole, a loading jack 48 disposed to be expandable/contractable on the device body 2b and having a loading rod 49 for applying a prescribed load on a hole bottom of the excavated hole 71, and measurement means 30 for measuring a position of the loading rod. The collapse prevention pipe 72s for an excavated hole supports the loading test device by bringing the fixing part of the loading test device into contact with an inner wall of the pipe
