Abstract: This invention provides a pluck-resistance measuring instrument for fastener members comprises a holder for pressing the fabric of a garment to which a fastener member is attached, securely around the member, a plurality of clamp members capable of clamping the fastener member and moving at right angles to the place where the fastener member is affixed to the fabric, and a tension detector for measuring the tensile force that is applied to the clamp members, wherein the holder is supported by a lift, the tension detector comprises a member providing a fulcrum, a mass lever pivotally supported at the fulcrum and a tension detector, the lever being coupled at one end to the clamp members and acts on the tensile detector at the other end as a tensile detector and a method for measuring the pluck resistance using the above instrument comprises the steps of (1) starting the lift to lower the holder.