A flush toilet has a reservoir tank, a toilet main unit, a water supply apparatus, a water discharge apparatus, and a control device for controlling flushing of the bowl portion of the toilet main unit; wherein this control device includes a time measurement device for measuring the time after the water discharge apparatus has been driven for a predetermined time to discharge flush water, until the water level rises from a dead water level inside the reservoir tank with the water discharge apparatus in an off state to a predetermined stopped water level prior to start of flush; and the driving time of the water discharge apparatus responsive to pressure losses in the toilet main unit is adjusted by comparing the water level rise time measured by the time measurement device with the water level rise time in a standard toilet.