PURPOSE: To enable easy engagement of a fixing pin weight thereof is even heavy with a pin hole by a method wherein the fixing pin is held on a crosshead supported by guiding frames and is engaged with and removed from the pin hole by an operating mechanism.

CONSTITUTION: A crosshead 1 is made to run along guiding frames 3 and 4 and the interval between crossheads 1 and 2 is adjusted according to the length of a piece to be tested. Fixing pins 12a and 12b held by the crosshead 1 are moved horizontally in accordance with the rotation of rotary axes 14a and 14b through displacement of the plunger 17 of a cylinder 16, thereby the fixing pins 12a and 12b are engaged with and removed from pin holes 11 of the guiding frames 3 and 4.