PROBLEM TO BE SOLVED: To obtain a foundation load testing method with which workability is improved while ensuring the settlement of a test version.SOLUTION: On a loading jack 20, a main girder 22 is installed via an upper pedestal 28. Both end portions 22A of the main girder 22 are coupled to a pair of a reaction pile 24 via a moving mechanism 30, respectively. The moving mechanism 30 comprises a movable carriage 32, a moving jack 34 and a reaction beam 36. The movable carriage 32 is hung from the both end portions 22A of the main girder 22 by a hanger 38. On the movable carriage 32, the reaction beam 36 is installed via the moving jack 34. The reaction beam 36 is coupled to a pile head 24A of the reaction pile 24 by an anchor 40. The upward movement of the reaction beam 36 is restricted by the anchor 40, and the moving jack 34 is capable of pressing the movable carriage 32 downward by using a reaction force to the reaction beam 36.