A method of welding laminated metal foils (LMF) by projecting a laser beam onto LMF sandwiched between an upper metal plate and a lower metal plate from a side of the upper metal plate and laser-welding the LMF to the upper metal plate and the lower metal plate. The method includes: forming a hole in an upper surface of the upper metal plate and forming a chamfered part so that a diameter of the hole expands toward the upper surface before the laser welding; and in the laser welding, projecting the laser beam for heat conduction welding onto the chamfered part of the upper metal plate to form a molten pool; and projecting the laser beam in a circle to agitate the molten pool and grow the molten pool in a laminating direction of the LMF so that the molten pool reaches the lower metal plate.