An aqueous liquid preparation, having a transmittance at wavelength 600 nm of not less than 98%, and comprising (3-{2-[4-isopropyl-2-(4-trifluoromethyl)phenyl-5-thiazolyl]ethyl}-5-methyl-1,2-benzisoxazol-6-yl)oxyacetic acid or a pharmaceutically acceptable salt thereof, and benzalkonium chloride represented by the formula: [C 6 H 5 CH 2 N(CH 3) 2 R]Cl wherein R is an alkyl group having 10, 12, 14, 16 or 18 carbon atoms; and wherein: the upper limit of a concentration of the benzalkonium chloride is 5 w/v% and the lower limit is 0.0001 w/v%, relative to the total amount of the aqueous liquid preparation; and wherein: R is an alkyl group having 10 carbon atoms, and the benzalkonium chloride contained therein has a concentration of less than 0.05 w/v% or higher than 0.1 w/v% relative to the total amount of the aqueous liquid preparation; or R is an alkyl group having 12 carbon atoms, and the benzalkonium chloride contained therein has a concentration of less than 0.003 w/v% or higher than 0.01 w/v% relative to the total amount of the aqueous liquid preparation; or R is an alkyl group having 14 carbon atoms, and the benzalkonium chloride contained therein has a concentration of less than 0.001 w/v% or higher than 0.002 w/v% relative to the total amount of the aqueous liquid preparation; or R is an alkyl group having 16 carbon atoms, and the benzalkonium chloride contained therein has a concentration other than 0.001 w/v% relative to the total amount of the aqueous liquid preparation; or R is an alkyl group having 18 carbon atoms; or the benzalkonium chloride comprises (i) a first benzalkonium chloride wherein R is an alkyl group having 12 carbon atoms and (ii) a second benzalkonium chloride wherein R is an alkyl group having 14 carbon atoms and the aqueous liquid preparation comprises a total concentration of the benzalkonium chloride of less than 0.001 w/v% or higher than 0.002 w/v% relative to the total amount of the aqueous liquid preparation. the upper limit of a concentration of the benzalkonium chloride is 5 w/v% and the lower limit is 0.0001 w/v%, relative to the total amount of the aqueous liquid preparation; and wherein: R is an alkyl group having 10 carbon atoms, and the benzalkonium chloride contained therein has a concentration of less than 0.05 w/v% or higher than 0.1 w/v% relative to the total amount of the aqueous liquid preparation; or R is an alkyl group having 12 carbon atoms, and the benzalkonium chloride contained therein has a concentration of less than 0.003 w/v% or higher than 0.01 w/v% relative to the total amount of the aqueous liquid preparation; or R is an alkyl group having 14 carbon atoms, and the benzalkonium chloride contained therein has a concentration of less than 0.001 w/v% or higher than 0.002 w/v% relative to the total amount of the aqueous liquid preparation; or R is an alkyl group having 16 carbon atoms, and the benzalkonium chloride contained therein has a concentration other than 0.001 w/v% relative to the total amount of the aqueous liquid preparation; or R is an alkyl group having 18 carbon atoms; or the benzalkonium chloride comprises (i) a first benzalkonium chloride wherein R is an alkyl group having 12 carbon atoms and (ii) a second benzalkonium chloride wherein R is an alkyl group having 14 carbon atoms and the aqueous liquid preparation comprises a total concentration of the benzalkonium chloride of less than 0.001 w/v% or higher than 0.002 w/v% relative to the total amount of the aqueous liquid preparation. R is an alkyl group having 10 carbon atoms, and the benzalkonium chloride contained therein has a concentration of less than 0.05 w/v% or higher than 0.1 w/v% relative to the total amount of the aqueous liquid preparation; or R is an alkyl group having 12 carbon atoms, and the benzalkonium chloride contained therein has a concentration of less than 0.003 w/v% or higher than 0.01 w/v% relative to the total amount of the aqueous liquid preparation; or R is an alkyl group having 14 carbon atoms, and the benzalkonium chloride contained therein has a concentration of less than 0.001 w/v% or higher than 0.002 w/v% relative to the total amount of the aqueous liquid preparation; or R is an alkyl group having 16 carbon atoms, and the benzalkonium chloride contained therein has a concentration other than 0.001 w/v% relative to the total amount of the aqueous liquid preparation; or R is an alkyl group having 18 carbon atoms; or the benzalkonium chloride comprises (i) a first benzalkonium chloride wherein R is an alkyl group having 12 carbon atoms and (ii) a second benzalkonium chloride wherein R is an alkyl group having 14 carbon atoms and the aqueous liquid preparation comprises a total concentration of the benzalkonium chloride of less than 0.001 w/v% or higher than 0.002 w/v% relative to the total amount of the aqueous liquid preparation.