To provide a grease supply device discharging a base oil smoothly by increasing the sealing property of an enclosed grease and extending the life of grease lubrication.

The grease supply device 4, which is provided in a fixed state to an outer ring 2, has an annular container part 11, the inner part of which becomes a grease reservoir, and an in-bearing insertion part 12, which protrudes from the container part 11 and which is inserted up to near the raceway surface 2a of the outer ring 2 to form a gap which makes the grease base oil ooze out to the tip. A grease sealing hole 13b which seals the grease, is provided in the container part 11 and a male screw member 16 which is screwed to this grease sealing hole 13b to seal the grease sealing hole 13b, is provided. The male screw member 16 is formed of a material having a larger thermal expansion coefficient than the container part 11.