Provided is a negative-electrode material powder used for a lithium-ion secondary battery having a large discharge capacity and sufficient cycle characteristics as being durable in use. The powder for the battery includes a conductive carbon film on a lower silicon oxide powder, surface and satisfies requirements that: Si in SiC is 15.1 wt % or less in content, or A3 (=A2−A1) is 15.1 or less, given A1 (wt %): Si content measured by acid solution process, and A2 (wt %): Si content measured by alkali solution process; and a specific resistance is 30,000 Ωcm or less. In the lower silicon oxide powder, a maximum value P1 of SiOx-derived halos appearing at 2θ=10° to 30° and a value P2 of the strongest line peak of Si (111) appearing at 2θ=28.4±0.3°, in XRD using CuKα beam, preferably satisfy P2/P1