Abstract: A benzoxazine compound-containing composition with a low melt viscosity, a curable resin composition, and a cured product thereof are provided. The benzoxazine compound-containing composition contains a benzoxazine compound represented by general formula (1) and a compound group (A) having a molecular weight in the range of 1,000 to 10,000. In a gel permeation chromatography measurement using a differential refractometer as a detector, a peak area of the compound group (A) is in the range of 0.1 area % to 15 area % relative to a peak area of all components detected, and the benzoxazine compound-containing composition has a melt viscosity at 100° C. in the range of 0.1 Pa·S to 4.5 Pa·S.