Aqueous dispersions of coal powder having good flowability properties are provided by employing, as the dispersing agent, an anionic surface active agent having the formula:[R--O--CH.sub.2 CH.sub.2 O--.sub.m SO.sub.3 ].sub.n Mwherein R is an alkyl or alkenyl group having 6 to 22 carbon atoms or an alkyl- or alkenyl-substituted aryl group having 4 to 22 carbon atoms in the substituent thereof, m is an integer of from 2 to 50, n is a number of from 1 to 3 and is the same as the valence of the counter ion M, and M is a cation having a valence of from 1 to 3.