A toner for developing electrostatic images includes (a) toner particles having a weight-average particle size of 1-9 .mu.m, (b) hydrophobized inorganic fine powder having an average particle size of 10-90 nm and (c) hydrophobized silicon compound fine powder. The hydrophobized silicon compound fine powder has an average particle size of 30-120 nm, and a particle size distribution such that it contains 15-45% by number of particles having sizes of 5-30 nm, 30-70% by number of particles having sizes of 30-60 nm and 5-45% by number of particles having sizes of at least 60 nm. The hydrophobized silicon compound fine powder having a broad particle size distribution including coarse particles functions to prevent the embedding of the hydrophobized inorganic fine powder (functioning as a flowability improver) from being embedded at the toner particle surfaces, whereby the toner is allowed to exhibit stable performances even in a continuous image formation on a large number of sheets.