To provide a wideband printed antenna that has radiation properties being omnidirectional on a horizontal surface over a wide band, and is advantageous in manufacturing costs and mounting.

The printed antenna has: coplanar track (the combination of an inner conductor 3 and grounds 4 each existing at the left/right of the inner conductor 3) formed by using a conductor thin film on a dielectric substrate 1; and a radiation element 2. The radiation element 2 has a slot 5, and the ground 4 of the coplanar track has a slot 6.