PURPOSE: To provide a protecting device for the grease nipple of a construction machine which is designed to reliably protect a grease nipple mounted on a part to be greased and perform the simple feed of grease.

CONSTITUTION: A collar 6 with which a grease nipple 2 mounted in the grease feed hole of a boss part 1 is surrounded is fitted in a hole 1a for mounting a collar formed in the boss part 1. A cover 7 is attached to the collar 6 by means of a hinge 8. A locking tool 7a on which a protrusion for locking intended to be fitted in a groove 6a for locking formed in the collar 6 is formed, integrally with the cover 7. Usually, the protrusion for locking the locking tool 7a is fitted in the groove 6a for locking and the cover 7 is fixed. When grease is fed, the cover is released from locking by the locking tool 7a and the cover 7 is rotated around the hinge 8 serving as a fulcrum.