PURPOSE: To obtain an economical non-destructive inspection method of a welded part for inspecting presence or absence of welding defect of the welded part of a specimen readily and non-destructively by a simple means.

CONSTITUTION: Electrodes are mounted to both welded members 1 and 2 which are welded each other, thus enabling electrical resistance between both welded members 1 and 2 to be measured. The presence or absence of welding defect is detected according to correlation of a joint rate corresponding to an electrical resistance which is obtained previously based on the property, dimensions, and the amount of welding of the members from the measurement values.