A seat air conditioning device that blows out air from a seat, supplied from an interior air conditioning unit that air-conditions a space in a passenger compartment for a vehicle, includes: a floor-side duct and a seat-side duct. The floor-side duct is disposed adjacent to a floor of a vehicle body member forming the space in the passenger compartment and is connected to the interior air conditioning unit. The air supplied from the interior air conditioning unit flows through the floor-side duct. The seat-side duct is disposed adjacent to the seat and communicates with the floor-side duct through a connecting duct. The connecting duct is configured to be deformed to follow displacement of the seat, and is arranged along a vehicle harness that connects a floor-side wiring member disposed adjacent to the floor and a seat-side wiring member disposed adjacent to the seat.