A valve device includes a valve, a drive device, and a transmission unit. A valve changes a flow mode of refrigerant that flows in a circulation path of a refrigeration cycle device. The transmission unit includes a driving-side rotary body, a magnetic transmission member, and a driven-side rotary body. The driving-side rotary body includes multiple magnetic magnet poles in a rotational direction. The magnetic transmission member includes multiple magnetic transmission bodies which are configured to be magnetized by the magnetic magnet poles. The driven-side rotary body includes multiple magnetic magnet poles in a rotational direction. The driven-side rotary body rotates in response to a rotary motion of the multiple magnetic magnet poles of the driving-side rotary body via the magnetic transmission body. The number of the magnetic magnet poles and the number of the magnetic transmission bodies are different from each other. The rotation is transmitted from the driving-side rotary body to the driven-side rotary body via the magnetic transmission member in a non-contact manner.