The effects were determined of the mass ratio of Geldart C particles on the total amount of particles (Mfine/Mtotal=0-50 wt%), superficial gas velocity (Ug=0.5-1.0 m/s) and coarse particle size distribution (mono, binary, flat, and Gaussian type) on entrainment of Geldart C particles in a bubbling fluidized bed with binary particles (coarse particles:dp=0.512 mm, ρs=2,339 kg/m3 and Geldart C particles: dp=13 μm, ρs=4,455 kg/m3). The initial entrainment rate increases with increasing Ug. At Ug of 0.5 and 0.7 m/s, the initial entrainment rate slightly increases initially and then remains almost constant with increasing mass ratio (Mfine/Mtotal). At higher gas Ug of 0.85 and 1.0 m/s, the initial entrainment rate increases with increasing the mass ratio (Mfine/Mtotal) up to 30 wt%, after which the increasing slope of the initial entrainment rate decreases with increasing the mass ratio (Mfine/Mtotal). Also, the decrease in the coefficient of entrainment rate is equal to the increase in (Mfine/Mtotal) at the corresponding Ug. The average particle size of the entrained particles is about 12-16 μm at Ug of 0.5-1.0 m/s.