The present invention realizes a thin dual-polarized leaky-wave antenna which uses a CRLH (Composite Right/Left Handed) transmission line and capable of obtaining a high tilt angle in a directivity in the vertical plane while suppressing cross polarization and side lobe at a target operation frequency.Specifically, the present invention provides a leaky-wave antenna including a dielectric substrate, a ground surface formed on a bottom surface of the dielectric substrate, a ground unit formed on a top surface of the dielectric substrate, and a CRLH (Composite Right/Left Handed) transmission line which is arranged adjacent to the ground unit and formed on a top surface of the dielectric substrate and uses a coplanar transmission line with a ground, in which a series capacitor (CL) and a parallel inductor (LL) constituting the CRLH transmission line are formed on a top surface of the dielectric substrate.