The invention provides a fatty acid alkyl ester sulfonate metal salt mixture of (a) a fatty acid alkyl ester sulfonate metal salt having an endothermic peak area at 50 to 130° C. of less than 50% relative to the whole endothermic peak area at 0 to 130° C. as measured on a differential scanning calorimeter, and (b) a fatty acid alkyl ester sulfonate metal salt having an endothermic peak area at 50 to 130° C. of 50% or more relative to the whole endothermic peak area at 0 to 130° C. as measured on a differential scanning calorimeter, with a ratio of (a) to (b) by mass of 95/5 or less. The mixture of the invention is excellent in anti-caking properties.