Laser beam printers can be substantial sources of submicron particles in the indoor environment. The present work investigated particle emissions from a commercial laser beam printer (LBP), which was one of single component, non-magnetic, non-contact mode type LBPs, in various operating conditions. Size distribution and number concentration of particles were measured by a scanning mobility particle sizer (SMPS). The size distribution of particles generated from the printer was 20-200nm in equivalent mobility diameter, regardless of the operating condition. When the fuser system was operated by fuser controller without development and the temperature of the heating roller was $190^{circ}C$, particles were detected and their peak concentration was about $10^3;particles/cm^3$ Zero percent coverage white papers and five percent coverage black papers, were used, the peak concentrations were $1.5{ imes}10^5;particles/cm^3$ and $3.3{ imes}10^5;particles/cm^3$, respectively. These results suggest that the sources of submicron particle generation were rubber of heating roller, paper, and toner.