A compact slot-type antenna has a dielectric interposed between a conductor plate and a stripline. The conductor plate has a slot, and the stripline has a first line section extending in a longitudinal direction of the slot and a second line section extending in a direction orthogonal to the first line section and having one end connected to the first line section. The first line section lies wholly within a projection area of the slot and is electromagnetically coupled to the conductor plate around the slot. A slit in the conductor plate extends from the slot to a side of the conductor plate which faces the first line section.