A laser build-up method according to an embodiment includes the processes of: forming an annular counter sunk groove 15 in an edge of an opening of a port on a side of a combustion chamber; and irradiating a laser beam 30 while a metallic powder 26 is being supplied to the counter sunk groove 15 and successively forming a cladding layer 16 for a valve seat, in which: the cladding layer 16 is formed while a seal gas 24 is being sprayed onto a melt pool 31, the cladding layer 16 includes a starting end part 17a, a part formed just after the starting end part is formed 18a, an intermediate part 18b, a part formed just before a terminating end part is formed 18c, and a terminating end part 17b, which are formed in this order.