A mobile communication base station antenna has a plurality of polarization diversity antenna blocks, each of the polarization diversity antenna blocks including a plurality of polarization diversity antenna elements, each of the polarization diversity antenna elements including antenna elements that are disposed to be orthogonal to each other. The polarization diversity antenna elements of one of the polarization diversity antenna blocks are interposed between the polarization diversity antenna elements of another one of the polarization diversity antenna blocks, and tilt angles in the vertical plane of the respective polarization diversity antenna blocks are different from each other.