The present invention relates to a bone-repair composition comprising a micro-pulverized demineralized bone matrix; a nonmicro-pulverized demineralized bone matrix; and a hydrating material. The bone-repair composition of the present invention provides easier injectability and shape-maintenance (handling), and exhibits excellent bone-repairing effects due to a large surface area of the micro-pulverized demineralized bone matrix and an early release of the bone growth factors, compared with conventional compositions comprising the nonmicro-pulverized demineralized bone matrix alone. It also has an advantage of being biocompatible and harmless to the human body because there is no use of synthetic materials.