An apparatus for measuring radiated power of an antenna includes a chamber which an absorber is attached to a wall thereof; a source antenna and a test antenna configured to be arranged within the chamber; a rotational axis configured to adjust an arrangement angle of the test antenna in up-and-down directions; and a roll positioner configured to rotate the test antenna. Further, the apparatus includes a turntable configured to be provided within the chamber and be rotated in a left-to-right direction; a connection unit configured to allow the test antenna, to rotate in the left-to-right direction; and a supporting unit configured to be rotatably connected to one end of the rotational axis which the other end thereof is rotatably connected to the roll positioner.