Device for measuring the torque of a hairspring

The device has a unit for maintaining an external end of a hairspring (5) with respect to an arbor during measurement of torque of the hairspring. The external end of the hairspring is integrated to a collet (5a). Diameter of a base of the arbor is dimensioned for permitting frictional driving connection with a wall of an axial opening of the collet. Elastic elements (2b) are conformed for bringing a section of a part of the base from a greater dimension to a dimension lower than the dimension of the axial opening of the collet under an action of an acting unit (7) e.g. nose plier. The hairspring is made of material e.g. silicon, quartz, diamond and silicon with silicon oxide coating. An independent claim is also included for a method for dynamically or statically measuring torque of a hair spring of a balance-spiral oscillator.