A toilet seat device includes a toilet seat, a casing provided in rear of the toilet seat, and a functional component that ejects liquid or that blows out or suctions gas. The functional component is a private part cleaning device that cleans a private part of a sitting person, a blower device that provides warm air into a toilet bowl, or a deodorizing device that deodorizes an inner portion of the toilet bowl, for example. At least part of the functional component is provided in the toilet seat, and the other part of the functional component is provided in the casing.