Dissimilar materials joining of an A5052 plate and a carbon fiber reinforced thermoplastic (CFRTP), which consisted of polyamide 6 (PA6) with 20 wt% carbon fiber addition, was performed using friction lap joining (FLJ) with the Al alloy plate as a top and the CFRTP plate as a bottom. The joint characteristics were evaluated to investigate effects of the surface treatment by the silane coupling treatment for A5052 and the joining speed on the joining properties. The joint strength was increased by inducing the silane coupling treatment for the A5052 plate surface. The tensile shear fracture load of the silane coupling treated FLJ joint increased with increasing the joining speed up to 6.67mm/s, and then decreased. The maximum tensile shear fracture load of 5.0kN was obtained at the joining speed of 6.67mm/s, and the fracture occurred at the CFRTP base plate with the joint efficiency of 97%. The shear strength of the joint interface of the joint formed at the joining speed of 1.67mm/s, which fractured at the joining interface by the tensile shear test, was estimated about 19MPa. The covalent bondings between the A5052 plate and the silane coupling layer, and the silane coupling layer and the CFRTP plate were indicated by inducing the silane coupling treatment.