The present invention relates to: a liquid composition suitable for the washing of a semiconductor element provided with a low-dielectric-constant interlayer insulating film; and a method for washing a semiconductor element. The liquid composition according to the present invention is characterized by containing tetrafluoroboric acid (A) in an amount of 0.01 to 30% by mass, or boric acid (B1) and hydrogen fluoride (B2) at a (boric acid)/(hydrogen fluoride) ratio of (0.0001 to 5.0/by mass)/(0.005 to 5.0% by mass), and having a pH value of 0.0 to 4.0. The liquid composition according to the present invention can reduce the damage of a low-dielectric-constant interlayer insulating film, cobalt or a cobalt alloy, alumina, a zirconia-based hard mask and a silicon nitride during the process of producing a semiconductor integrated circuit, and accordingly can be used suitably for removing dry etching residues occurring on the surface of the semiconductor integrated circuit.