The photoinduced magnetization in magneto-optical crystal terbium gallium garnet (TGG) is investigated by time-resolved pump-probe spectroscopy. When the pump pulse is elliptically polarized, the rotation signal and the ellipticity signal of the probe pulse are observed at zero time delay, resulting from the optical Kerr effect and the inverse Faraday effect. The direction of the effective magnetic field is dominated by the helicity of the pump pulse, so the rotation signal and the ellipticity signal of the probe pulse can be triggered selectively by modifying the helicity of the pump pulse. The full widths at half maximum of the rotation signal and the ellipticity signal both can be as fast as about 500 fs, which indicates that TGG crystal is expected to be a candidate material of ultrafast all-optical magnetic switching.