Patent ID: 8701301

Claim:
A surface texture measuring instrument comprising: a measurement arm that is supported by a body movably in a circular movement around a rotary shaft; a stylus provided at an end of the measurement arm; a displacement detector that detects a circular movement amount of the measurement arm; a detector having a casing that houses the body; a stage on which an object to be measured is mounted; and a relative movement mechanism that moves the detector and the stage relatively to each other, the surface texture measuring instrument being configured to detect the circular movement amount of the measurement arm by the displacement detector while moving the detector and the stage relatively to each other by the relative movement mechanism with the stylus being in contact with a surface of the object and to measure a surface texture of the object based on the circular movement amount, wherein the measurement arm comprises: a first measurement arm that is supported by the body swingably around the support shaft in the casing; and a second measurement arm that is provided with the stylus at an end thereof and is detachably provided to an end of the first measurement arm via an attachment-detachment mechanism, the attachment-detachment mechanism being arranged in the casing, the displacement detector comprises: a scale that is provided to one of the body and the measurement arm; and a detection head that is provided to the other of the body and the measurement arm to face the scale, and a detecting surface of the scale is on an axis of the measurement arm and on a plane of the circular movement of the measurement arm.