A phased array transmission device comprising: a first transmission branch and a second transmission branch, each including: a transmitter (171,172), configured to transmit a transmission signal in a wireless frequency; a phase adjuster (181,182), configured to adjust a phase of the transmission signal; an amplitude adjuster (191,192), configured to adjust an amplitude of the transmission signal; an antenna section (11,12), configured to radiate an output signal from the transmitter (171,172) into a space; and a coupler section (161, 162), configured to extract a part of an output from the transmitter (171,172); a signal combining section, configured to combine outputs from the coupler sections (161, 162) of the first and second transmission branches (101,102); a combination detector, configured to detect a level of an output from the signal combining section; and a phase controller configured to control the phase adjuster (181,182) according to the output detected by the combination detector; characterized by a first branch detector and a second branch detector, configured to detect levels of outputs from the coupler sections (161, 162) of the first and second transmission branches (101,102), respectively; and an amplitude controller, configured to compare two detection outputs for the output levels detected by the first and second branch detectors, and control at least one of the amplitude adjusters (191,192) such that the two detection output levels are conformed to each other in a case where the two detection outputs are not the same. a first transmission branch and a second transmission branch, each including: a transmitter (171,172), configured to transmit a transmission signal in a wireless frequency; a phase adjuster (181,182), configured to adjust a phase of the transmission signal; an amplitude adjuster (191,192), configured to adjust an amplitude of the transmission signal; an antenna section (11,12), configured to radiate an output signal from the transmitter (171,172) into a space; and a coupler section (161, 162), configured to extract a part of an output from the transmitter (171,172); a transmitter (171,172), configured to transmit a transmission signal in a wireless frequency; a phase adjuster (181,182), configured to adjust a phase of the transmission signal; an amplitude adjuster (191,192), configured to adjust an amplitude of the transmission signal; an antenna section (11,12), configured to radiate an output signal from the transmitter (171,172) into a space; and a coupler section (161, 162), configured to extract a part of an output from the transmitter (171,172); a signal combining section, configured to combine outputs from the coupler sections (161, 162) of the first and second transmission branches (101,102); a combination detector, configured to detect a level of an output from the signal combining section; and a phase controller configured to control the phase adjuster (181,182) according to the output detected by the combination detector; characterized by a first branch detector and a second branch detector, configured to detect levels of outputs from the coupler sections (161, 162) of the first and second transmission branches (101,102), respectively; and an amplitude controller, configured to compare two detection outputs for the output levels detected by the first and second branch detectors, and control at least one of the amplitude adjusters (191,192) such that the two detection output levels are conformed to each other in a case where the two detection outputs are not the same.