WELDING METHOD OF METALLIC MEMBER

PROBLEM TO BE SOLVED: To measure a penetration depth during welding at real time and to further prevent occurrence of a defective penetration by changing a welding condition on the basis of the measured result. SOLUTION: In the welding method of metallic members in which two metallic members (steel plate 1, 2) are welded and a weld joint of a specified penetration depth is obtained, during welding, an ultrasonic wave is incident from a surface of one metallic member to a specified penetration depth position P of the metallic member, by a reflected wave or a transmitted wave of the ultrasonic wave, whether an end part 8a of a molten pool is reached or not to the specified penetration position P is detected, when the end part 8a of the molten pool does not reach the specified penetration depth P, welding is performed by changing welding condition so that the specified penetration depth may be obtained.