In a previous study, the effects of the bonding conditions (bonding temperature, pressure, surface roughness, interlayer, electric current wave) on joint efficiency were investigated using 5052Al and 6063Al joints during pulsed electric current bonding. The results were found as follows. The surface roughness and current waveform (direct current, duty ratio, pulse frequency) show no effect on the joint strength. With an increase of the bonding temperature and pressure, the deformation of the joints increase. The bonding temperature and pressure have to be selected in way to prevent significant deformation of the joint configuration. In the current study, the effect of the post heat treatment on the joints is under investigation to improve the joint strength of 5052Al and 6063Al. Post heat treatments for the 5052Al and 6063Al joints improves the strength of both of them. The effect of the post heat treatment for the 6063Al joint is larger than the effect for the 5052Al joint. Post heat treatment performed on the joints promoted a Mg reduction mechanism by in Al alloys to remove an oxide film at the bond inteface. Based on the tensile properties and the microstructure of the joints, an optimum added amount of Mg in order to improve the joint properties of the Al alloy was determined to be 0.3-1 mass%. Using a solution and aging heat treatment, the joint properties of 6063Al equals the joint properties of a base metal.