SPARK PLUG

An object is to efficiently conduct heat from a tip to an inner layer to thereby improve the corrosion resistance of the tip. A spark plug 1 includes a ceramic insulator 2 having an axial hole 4 extending in the direction of an axis CL1, a center electrode 5 inserted into the axial hole 4, a metallic shell 3 provided around the ceramic insulator 2, a ground electrode 27 fixed to a forward end portion of the metallic shell 3, and a tip 32 joined to a distal end portion of the ground electrode 27 and forming a spark discharge gap 33 between the tip 32 and a forward end portion of the center electrode 5. The ground electrode 27 includes an outer layer 27A and an inner layer 27B provided inside the outer layer 27A and formed of a metal which contains copper as a main component. The tip 32 is joined to the ground electrode 27 by a fusion portion 35 which contains a metal which forms the tip 32 and a metal which forms the outer layer 27A. The fusion portion 35 is in contact with the inner layer 27B and contains copper.