A valve device includes a shaft, a housing defining a flow passage and having a plurality of openings, and a first movable disk and a second movable disk being rotatable. The plurality of openings includes one-side openings and other-side openings. The housing includes a one-side partition wall partitioning the flow passage into a plurality of one-side flow passages and an other-side partition wall partitioning the flow passage into a plurality of other-side flow passages. The first movable disk is rotated to switch a one-side flow passage communicating with a first through-hole. The second movable disk is rotated to switch an other-side flow passage communicating with a second through-hole.