A structural unit having a net member incorporated therein capable of preventing local application of undue force to the net member, to thereby increase reliability of the net member. An end section of a net member of a three-dimensional structure is treated so as to be reduced in cushioning characteristics and increased in hardness as compared with a portion of the net member positioned inside the end section. A frame constituting a part of the structural unit is provided with an end holding member so that an insertion port of an insertion gap of the end holding member is arranged in a particular direction or posture, resulting in the end section being readily held in the holding member by merely inserting the end section in the insertion gap. The end section is entirely inserted into the insertion gap, so that application of load to the end section may be carried out in a two-dimensional manner rather than a spot-like manner. This prevents local application of load to the net member, to thereby keep the net member from damage thereto.