Structural unit having net member incorporated therein, seat and method for treating end section of net member

A structural unit comprising:

• a net member of a three-dimensional structure constituted by a front mesh layer, a rear mesh layer and a plurality of piles arranged between said front mesh layer and said rear mesh layer so as to connect said front mesh layer and rear mesh layer to each other therethrough;
• said net member being formed on a periphery thereof with an end section;
• and
• an end holding member for supporting said end section of said net member therein;
• said end holding member including a holding element formed therein with an insertion gap into which said end section of said net member is inserted;
• said end section of said net member being treated so that at least a part thereof has a net structure increased in density and rigidity as compared with a portion of said net member positioned inside said end section, resulting in being held in said end holding member due to insertion thereof into said insertion gap of said end holding member;
• wherein said end section is treated so as to be reduced in thickness by heat welding, so that said net structure is increased in density and rigidity;
• and
• wherein said end section is subject to said heat welding after said end section is previously knitted so as to increase density of said net structure.