Superrotation of more than 100 m s-1 is formed at the cloud top (65--70 km) in a T21 Venus-like atmospheric general circulation model (Venus-like AGCM) driven by a zonal-mean thermal forcing. This is maintained by the Gierasch mechanism, in which meridional circulation efficiently pumps up angular momentum and various waves produce equatorward eddy momentum fluxes. In addition to the above mechanism, fast equatorial waves with a wide frequency range (including a famous 4-day wave) enhance the cloud-top superrotation, since the downward angular momentum flux of vertically propagating gravity waves is canceled by the upward flux of the fast equatorial waves.