According to one embodiment, a toilet seat device includes a toilet seat, a sterilizer, a sprayer, a blower, and a controller. The sterilizer generates sterilizing water. The sprayer sprays a mist of the sterilizing water into a flush toilet. The blower generates a rising air stream. The controller controls the sprayer to simultaneously generate first and second mists in a state in which the blower generates a first rising air stream. The first mist has a particle size liftable toward the toilet seat by the first rising air stream. The second mist is generated to have a particle size larger than that of the first mist and not to be lifted toward the toilet seat by the first rising air stream. The sprayer causes a total amount of the first mist to be less than that of the second mist.