Abstract: The improved sample holder comprises a cylinder portion 5 having a center hole through which a test piece is inserted, a reciprocating ram rod 7 that is inserted into said hole and which is vertically slidable under hydraulic pressure to push down the test piece, and a test piece fixing plate 6 that is inserted under the cylinder portion 5 as it is slid horizontally from either right or left, with the thicker part of the test piece being held between the fixing plate 6 and the working end of the hydraulically operated pushing rod 7. The holder permits a fatigue test piece to be mounted and fixed on a testing machine by remote manipulation so that a fatigue test can be performed in either a hot vacuum or inert gas atmosphere.