A multi-frequency antenna having a small size, light weight and excellent productivity and being suitable for transmitting and receiving electric waves in Ghz band, is constituted such that an orthogonal coordinate X-Y is set, a first antenna element 21 having an electric wavelength of λa/4 and a second antenna element 22 having an electric wavelength of λb/4 are placed in parallel to the X axis respectively, one edge of each of said elements is positioned near the Y axis, said two elements are connected electrically with a ground plate 8 by a short-circuit line 4 along the Y axis, a point where an impedance is 50 Ω (code 50) of the first antenna element 21 and a point where an impedance is 50 Ω of the second antenna element 22 are made to be a power feed point respectively, and said power feed points are connected with a coaxial cable 7 through a power feed line 6.