Surface texture measuring instrument

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 measurement force applier that applies a measurement force to the stylus by biasing the measurement arm in circular movement directions;
• 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 movably in the circular movement around the support shaft;
• 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 measurement force applier comprises a voice coil that biases the measurement arm in the circular movement directions around the support shaft, and a balance adjuster that adjusts electric current passing through the voice coil to adjust balance of the measurement arm, after the second measurement arm is exchanged.