This invention relates to a tri(lower alkoxy)benzene derivative of the general formula (I), or its salt, optical isomer or solvate, ##STR1## wherein: R.sup.1, R.sup.2 and R.sup.3 : same or different and each represents a lower alkyl group;A: a group of the formula ##STR2## and R.sup.4 and R.sup.5 : same or different and each represents a lower alkyl group, an aralkyl group or an aryl group, provided that R.sup.4 and R.sup.5 may, taken together with the adjacent nitrogen atom, form a pyrrolidinyl group, a piperidino group, a morpholino group, a thiomorpholino group, or a piperazinyl group optionally substituted by a lower alkyl group in 4-position;to pharmaceutical compositions containing the same, and to processes for their production. The compound of the invention is useful as value as a pulmonary-surfactant secretion promoting agent.