A pressure fluctuation buffering mechanism includes a buffer space connected to a brush via a paint flow space (a paint tank and a paint feeder) through which paint flows. The pressure fluctuation buffering mechanism buffers pressure fluctuations in the paint tank by the flow of paint and air between the paint flow space and the buffer space. The pressure fluctuation buffering mechanism includes a first buffer space forming member for forming a first buffer space in the buffer space, and a second buffer space forming member for forming a second buffer space in the buffer space. The paint between the first buffer space and the paint flow space flows more easily than the paint between the second buffer space and the paint flow space.