The present disclosure relates to a stable liquid composition comprising a botulinum toxin as an active ingredient which is ready-to-use without the need for a reconstitution process, and particularly, to a liquid composition capable of preventing the botulinum toxin from aggregating even when the botulinum toxin is contained at a low concentration to thereby exhibit high stability, and efficiently preventing adsorption, etc., to a container, to constantly maintain an activity of the botulinum toxin for each batch or for each liquid vial. Specifically, the present disclosure relates to the liquid composition comprising (i) a botulinum toxin as an active ingredient, (ii) L-alanine or methyl cellulose, (iii) a non-ionic surfactant, and (iv) a buffer, and optionally, an isotonic agent. The liquid composition of the botulinum toxin according to the present disclosure is which is ready-to-use without performing a reconstitution process, and thus, it is possible to improve user's convenience, and reduce a deviation of botulinum toxin activity, etc., due to dilution errors in the reconstitution process, etc. Further, the liquid composition according to the present disclosure efficiently prevents the botulinum toxin from aggregating even at a low botulinum toxin concentration to thereby have extremely excellent storage stability, and efficiently prevents adsorption of the botulinum toxin to a container, thereby constantly maintaining an activity of the botulinum toxin for each batch or for each liquid vial.