Abstract: Footwear with unstable sole structure for statically optimal body posture and healthy dynamics comprising an upper and a sole structure attached to the upper, the sole structure having a wearing layer contacting the ground, a bottom layer attached to the wearing layer, an upper layer attached to the bottom layer, and a stiffener plate contacting the upper layer. A bottom layer covering the tread surface is attached to the wearing layer extending at least over the side surfaces of the bottom layer, An upper layer covering the tread surface is attached to the bottom layer, the upper layer comprising a support projection dimensioned to at least match the print of the arch of the foot, with the material of the bottom layer being more resilient than that of the upper layer. The stiffener plate contacting the upper layer covers the tread surface with a cross-section decreasing towards the toes.