The present invention is a negative electrode active material for a negative electrode active material layer of a lithium ion secondary battery, wherein: the negative electrode active material comprises silicon-based material consisting of SiOx (0.5≤x≤1.6); and the negative electrode active material has two or more peaks in a region of a bond energy ranging from 520 eV to 537 eV in an O 1s peak shape given in an X-ray photoelectron spectroscopy. As a result, it is possible to provide a negative electrode active material in which a battery capacity can be increased and cycle characteristics and initial charge/discharge characteristics can be improved when used as a negative electrode active material for a lithium ion secondary battery.