To reduce required portions for friction agitation jointing to 1/2 or less, remove generation of jointing part failures due to opening of a butt part even if a width direction constraining portion is omitted, remove necessity of manufacture/set of a special joint for jointing, remove necessity of grinding/ polishing after jointing since a rotation/movement locus is not left on a product decorative face, improve productivity dramatically, and reduce facility costs and manufacturing costs.
This hollow panel structural element comprises a pair of hollow extrusion shaped materials 1, 1. Then, the element is equipped with a lower part engagement part 5b, wherein lower part engaged parts 1Aib, 1Bib formed to width direction ends 1A, 1B of each hollow extrusion shaped material are engaged with each other. Also, a friction agitation jointing part 6 is provided to a butt part 2, wherein butted parts 1Au, 1Bu formed on one face plate 1up, 1bp out of a pair of top and reverse face plates 1up of a pair of the hollow extruded shape materials are butted each other, so as to constitute a main part.
MAKITA SHINYA