An active material comprising silica-attached particles in the form of host particles of silicon or silicon compound having spherical silica nano-particles attached to surfaces thereof is suited for use in nonaqueous electrolyte secondary batteries. The spherical silica nano-particles have an average particle size of 5-1000 nm, a particle size distribution D90/D10 of up to 3, and an average circularity of 0.8-1. The active material has high fluidity and exhibits improved cycle performance when used in nonaqueous electrolyte secondary batteries.