The present invention provides a flush toilet device (1) including: a flush toilet (2); a flush water tank (10); a discharge valve (12) that discharges the flush water stored in the flush water tank; a branching portion (33) that splits flush water supplied from a water supply source into first and second branched flow paths; a first on-off valve (19) provided in the first branched flow path and switches between spout and stop of the flush water from the upper spout port; a second on-off valve (17) provided in the second branched flow path and switches between supply and stop of the flush water into the flush water tank; and a controller (28) that controls the first and second on-off valve so that water is spouted from the upper spout port and is supplied into the flush water tank at a time by opening the first and second on-off valves.