In a frictional stirring weld apparatus for bonding elements with a rotary tool, a head is movable with respect to the elements to position and orient the rotary tool so that a pin of the rotary tool is aligned along a boundary between first surfaces and a shoulder of the rotary tool faces to second surfaces extending radially outward from the first surfaces, and to generate a relative movement between the rotary tool and the elements along the second surfaces, and a compensating member is capable of holding thereon the rotary tool, at least partially rotatable on the rotational axis with respect to the head to rotate the rotary tool, and supported on the head movably along the rotational axis with respect to the head so that a positional relationship between the rotary tool and a combination of the elements is adjustable in a direction parallel to the rotational axis.