PURPOSE: To carry out the thread pulling-out test which can be executed easily by constituting the detection means for a caulking device from a member which contacts the original edge surface of an eyeless needle and shifts, accompanied with the shift in the thread pulling-out direction and a means for detecting the shift.

CONSTITUTION: A fine displacement is generated on the lower mold 4 by allowing a thread pulling-out force to act on an eyeless needle 1 which is temporarily pressed by molds 4 and 5 through an anastomosis thread 2, and this displacement is detected by a detecting means, and the thread pulling-out test can be executed. On the figure, a pressure sensitive sensor 41 which acts as detecting means through the contact with the lower mold 4 is arranged, and fixed on a bracket 42 installed on a frame 6. When the thread pulling-out force in the direction of arrow (d) is applied on the anastomosis thread 2 in the state where the eyeless needle 1 is nipped by the upper and lower molds 5 and 4, the thread pulling-out force is transmitted to the molds 4 and 5 through the eyeless needle 1, and a fine deflection is generated on the lower mold 4 according to the value of the thread pulling-out force. The deflection of the lower mold 4 is detected by the pressure sensitive sensor 41, and the value of the thread pulling-out force can be detected by the deflection of the lower mold 4 by connecting the pressure sensitive sensor 41 with a conversion part.