Abstract: An arch support orthotic device comprises an upper surface facing a wearer's foot, and a lower surface facing a footwear, wherein the upper surface is formed of a deformable semi-rigid material responding flexibly to a weight of the wearer, and wherein the lower surface comprises an arch support section facing an inner sole surface of the footwear including a plurality of support structures that performs an arch supporting function, controls a deformability of the orthotic device so as to reduce loss of the arch supporting function when worn by the wearer, and prevents substantial deformation against the inner sole surface of the footwear.