A distortion correcting device is accommodated at a concave portion of the neck of a stringed instrument, and includes a bar including a bottom plate portion and a pair of opposing side plate portions erected at both sides of the bottom plate portion; and an adjusting rod whose one end portion is secured to one end portion of the bar and whose other end portion engages with an adjusting nut which is rotatably supported by the other end portion of the bar, and in which the distance between the one end portion of the adjusting rod and the adjusting nut can be changed by turning the adjusting nut. A first support member and a second support member are secured to the side plate portions at both end portions of the bar, and one end portion of the adjusting rod is supported such that movement in an axial direction is blocked by the first support member, and the adjusting nut is rotatably supported by the second support member.