The effect of mono-(MEA), di-(DEA), tri-(TEA) ethanolamines was investigated on the properties of silica aerogels prepared from tetramethoxysilane (TMOS) by methanol supercritical drying. The ethanolamines function as base catalysts for sol-gel process. Gelation time increased with decrease of pKa value (Ka is acidity constant of conjugated acid of the catalysts in aqueous solution) of a catalyst. The constituent particle sizes in silica aerogels increased with the increase of the gelation time. Shrinkage of alcogels was observed even in the methanol supercritical drying. Aerogel bulk densities were influenced mainly by the shrinkage of the alcogels. The aerogel with relatively lower bulk density was obtained at the molar ratio of catalyst to TMOS of 0.001, irrespective of the kind of the catalyst.