A toilet seat device according to an embodiment is a toilet seat device configured to be attached to an upper part of a closet bowl on which a bowl part for receiving excrement is formed, and includes: a toilet seat upper plate constituting a seating surface on which a user sits; a toilet seat bottom plate joined with the toilet seat upper plate to be opposed to an upper part of the closet bowl; a heating device disposed between the toilet seat upper plate and the toilet seat bottom plate to heat the toilet seat upper plate; and a detection device disposed on the toilet seat to optically detect the excrement. The detection device is arranged in a non-contact manner with respect to the heating device.