PURPOSE: To easily insert a brush to a narrow-mouthed container and to easily wash the bottom of the bottle by using a shape memory alloy, which is deformed by heat, for an opening and closing part between a main body part and a washing elastic part and the washing elastic part.

CONSTITUTION: The brush is normally set in a state that an opening closing part 2 is closed. Then, the brush can be easily inserted from a bottle port part 53 of a feeding bottle 5. A main body part 1 is equipped with the opening and closing part 2, which is composed of the shape memory alloy, to be opened by heating in an interval to a washing elastic part 3. Accordingly, the opening and closing part 2 is opened at 90° by hot water 6 in the feeding bottle 5. Since the washing elastic part 3 is composed of a linear body 33 of the shape memory alloy to be bent by heating in correspondence to the bottom part shape of the feeding bottle 5, the washing elastic part 3 is bent in the same shape as the opening and closing part 2 by the hot water 6 in the feeding bottle 5. A nylon-made brush part 35 is fitted around the linear body 33. Thus, a solidified substance 7 of milk remained in a bottle bottom 51 of the feeding bottle 5 can be easily washed and removed by the washing elastic part 3.