The present invention relates to a negative electrode active material including an Si—Sn—Fe—Cu based alloy, in which an Si phase has an area ratio in a range of from 35 to 80% in the entire negative electrode active material, the Si phase is dispersed in a matrix phase, the matrix phase contains an Si—Fe compound phase crystallized around the Si phase and further contains an Sn—Cu compound phase crystallized to surround the Si phase and the Si—Fe compound phase, the Si—Fe compound phase is crystallized in a ratio of from 35 to 90% in terms of an area ratio in the entire matrix phase, and the matrix phase further contains an Sn phase unavoidably crystallized in the matrix phase in a ratio of 15% or less in terms of an area ratio in the entire matrix phase.