This flush toilet apparatus includes a traveling-direction switching mechanism switching a mode between a toilet washing mode and a tank storage mode. This traveling-direction switching mechanism includes: a shield portion directing jet water to an outside of a throat pipe at a time of the tank storage mode; a moving mechanism moving the shield portion from a position at a time of the toilet washing mode in a first direction to a position at the time of the tank storage mode; and a guide surface switching a traveling direction of the jet water so that after the traveling direction is switched, a flow rate of the jet water is higher in a second direction opposite to the first direction than in the first direction.