A phased array antenna apparatus includes a plurality of radiation elements, a power supply unit, a power distributor, a feed probe, a plurality of electromagnetic coupling units, and a plurality of phase shifters. The radiation elements are aligned and arranged to be electromagnetically driven. The power supply units supply power to the radiation elements. The power distributor has a pair of conductive plates arranged to be parallel to each other and acts as a radial waveguide distributing the power supplied from the power supply unit to the radiation elements. The feed probe is arranged on one of the conductive plates to radiate an electromagnetic wave into the radial waveguide in accordance with the power supplied from the power supply unit. The electromagnetic coupling units are arranged on the other conductive plate in correspondence with the radiation elements to extract the electromagnetic wave radiated from the feed probe and propagating through the radial waveguide by electromagnetic coupling. The phase shifters control a phase of the electromagnetic wave extracted by the electromagnetic coupling units and supply the electromagnetic wave to the radiation elements.