A connection unit , which is magnetically connectable to other connection units into an assembly, comprising: a body having a substantially flat plate shape and peripheral edges; a plurality of magnets , at least one of which being disposed on each side of the peripheral edges of the body ; and a plurality of electrode terminals , at least three of which being disposed on the each side of the peripheral edges of the body , wherein an outer surface of the each side of the body has a curved surface which curves in a thickness direction or a surface having a polygonal cross section, the electrode terminals are disposed along the curved surface or the surface having the polygonal cross section of the outer surface , and the at least three electrode terminals disposed on the each side of the peripheral edges of the body comprise either: one positive electrode terminal and two negative electrode terminals , the positive electrode terminal being disposed at a center of the respective side of the peripheral edges of the body and the negative electrode terminals being disposed line-symmetrical about a perpendicular line perpendicular to and crossing the center of the respective side of the body , or one negative electrode terminal and two positive electrode terminals , the negative electrode terminal being disposed at the center of the respective side of the peripheral edges of the body and the positive electrode terminals being disposed line-symmetrical about the perpendicular line perpendicular to and crossing the center of the respective side of the body . a body having a substantially flat plate shape and peripheral edges; a plurality of magnets , at least one of which being disposed on each side of the peripheral edges of the body ; and a plurality of electrode terminals , at least three of which being disposed on the each side of the peripheral edges of the body , wherein an outer surface of the each side of the body has a curved surface which curves in a thickness direction or a surface having a polygonal cross section, the electrode terminals are disposed along the curved surface or the surface having the polygonal cross section of the outer surface , and the at least three electrode terminals disposed on the each side of the peripheral edges of the body comprise either: one positive electrode terminal and two negative electrode terminals , the positive electrode terminal being disposed at a center of the respective side of the peripheral edges of the body and the negative electrode terminals being disposed line-symmetrical about a perpendicular line perpendicular to and crossing the center of the respective side of the body , or one negative electrode terminal and two positive electrode terminals , the negative electrode terminal being disposed at the center of the respective side of the peripheral edges of the body and the positive electrode terminals being disposed line-symmetrical about the perpendicular line perpendicular to and crossing the center of the respective side of the body . one positive electrode terminal and two negative electrode terminals , the positive electrode terminal being disposed at a center of the respective side of the peripheral edges of the body and the negative electrode terminals being disposed line-symmetrical about a perpendicular line perpendicular to and crossing the center of the respective side of the body , or one negative electrode terminal and two positive electrode terminals , the negative electrode terminal being disposed at the center of the respective side of the peripheral edges of the body and the positive electrode terminals being disposed line-symmetrical about the perpendicular line perpendicular to and crossing the center of the respective side of the body . <EOS>