A digital displacement measuring instrument includes a spindle screwed into a body to be axially advanced and retracted relative to the body; and an encoder that detects a displacement of the spindle. The encoder includes a rotor and a stator. The rotor is supported by a rotor bushing. The rotor bushing includes an engaging key engageable with a key groove axially provided on the outer circumference of the spindle, and is displaceable in the axial direction of the spindle via a position adjusting screw. The stator is fixed to the body via a stator bushing in the vicinity of the spindle so as not to be displaceable in the axial direction of the spindle.