To provide a bearing device for a water pump capable of improving durability by suppressing the abrasion of a seal member.

The bearing device for the water pump includes: a rolling bearing 50 for rotatably supporting a rotary shaft 40 of the water pump on a housing 10; and the seal member 70 that is arranged between the inner peripheral surface of one end of an outer ring 51 of the rolling bearing 50 and the outer peripheral surface of the rotary shaft 40 and seals the inside of the rolling bearing 50. A retainer 60 for rollably retaining a rolling element 55 of the rolling bearing 50 is made of synthetic resin mixed with reinforced fiber. A coating layer 68 is disposed on at least the side of the retainer 60 facing the seal member 70.