Magnetic pulse welding was applied to the lap joining of similar (Al/Al) and dissimilar materials (Al/Fe, Al/Cu, and Al/Ni). The magnetic pulse welding is a kind of impact welding represented by explosive welding. The impact energy is induced by electromagnetic force generated by interaction among discharge pulse, induced magnetic flux, and eddy current produced at the plate surface. The welding was achieved within 10 microseconds with a negligible temperature increase. The welding interface exhibited a characteristic wavy morphology, which was similar to that of the explosive welding. In the Al/Fe, Al/Cu, and Al/Ni joints, an intermediate phase layer was produced along the wavy interface. In order to investigate microstructure of the intermediate phase layer, TEM observation of the welding interface was carried out. TEM observation revealed that the intermediate phase layer consisted of amorphous phase and fine crystal grains.