In this article, a wideband planar magneto-electric (ME) tapered slot antenna (TSA) with wide beamwidth both in the E-plane and H-plane is investigated. By simply etching slots on the basic TSA, which can function as a combination of magnetic dipole and electric dipole, stable unidirectional patterns with wide beamwidth are obtained. The metal ground plane is further modified to realize wide beamwidth across a wide frequency bandwidth. Moreover, a double-layer structure is employed to suppress the cross polarization. The measured results show that the proposed antenna can achieve an impedance bandwidth of 51.7% (7.22-12.25 GHz) with a stable gain of 2.3 dBi, and a pattern bandwidth of 43% (7.8-12.2GHz) for more than 135° half-power beamwidth. The measured front-to-back (F/B) ratio is more than 15 dB in the pattern bandwidth.