A wireless power transmission device includes: a power transmission antenna to transmit power by radiating a radio wave; a radiation direction determiner to determine a radiation direction. The power transmission antenna is a phased array antenna including: a plurality of element antennas to radiate the radio wave; and a plurality of element modules, each of the plurality of element modules including a phase shifter to change a phase of the transmission signal. An orientation direction is changed to the radiation direction by controlling a phase shift amount of the phase shifter. A phase offset value for the phase shifter included in each of the plurality of element modules is calculated by performing a REV method using a hovering aerial moving body hovering above the power transmission antenna. The phase shifter changes the phase by an amount obtained by subtracting the phase offset value from the phase shift amount.