PURPOSE: To obtain a polished surface which is smooth and glossy with ease by contg. a specific silicic acid-contg. material together with a heavy metallic salt catalyst in Al chemical polishing liquid contg. caustic soda and nitrate and/or nitrite.

CONSTITUTION: A silicic acid-contg. material selected from alkali silicate and bentonite is contained together with a heavy metallic salt catalyst in Al chemical polishing liquid cosisting of aq. liquid contg. caustic soda and ≥1 kind of nitrate and nitrite. If the resultant alkaline Al chemical polishing liquid is held at about 80W110°C and an Al material to be polished is dipped therein, the polished surface which is smooth and glossy is obtained with ease. Here the heavy metallic salt catalysts which promote the conversion of nitrate ions to nitrite ions, for example, copper salts, cobalt salts, etc. are preferable.