PURPOSE: To facilitate disposal of waste grease accumulated in a waste grease container so that surroundings and hands are not contaminated.

CONSTITUTION: An annular groove 3a is provide on the inner periphery of a discharge port 3 for waste grease 9 of a bearing box 1. A protruded line 12 is provided on the outer periphery of an opening 11 of a waste grease container 10 made of rubber or synthetic resin to be attached and detached to from the groove 3a. The container 10 in which the waste grease 9 is filled up is removed from a bearing device and disposed off as it is, and then a new container 10 is re-installed. Therefore, the waste grease 9 accumulated in the container 10 can be disposed off easily. If the container 10 is made transparent or semi-transparent, judgment of disposal time will easier and, from the color and state of the waste grease 9, the abnormal state, etc., of the bearing can be detected. If the container 10 is so designed that it is provided with restoring force, the waste grease 9 at the inner part of the discharge port 3 can be sucked positively.