Micrometer

A micrometer comprising:

• a body;
• a fixed sleeve that is fixed to the body;
• a spindle that is screwed to the fixed sleeve and is axially advanced and retracted;
• a thimble that is rotatably fitted to an outer circumference of the fixed sleeve and has an outer end connected to the spindle;
• an operation sleeve fitted over a range from an outer circumference of the thimble to an outer end of the spindle and being rotatable relative to the thimble;
• and
• a constant pressure mechanism that is disposed between the operation sleeve and the spindle, the constant pressure mechanism transmitting a rotation of the operation sleeve to the spindle and allowing a free rotation of the operation sleeve against the spindle when a predetermined or more amount of load is applied on the spindle, wherein
• a bearing member is disposed between the thimble and the operation sleeve, and the bearing member is provided by a rolling bearing.