To prepare an oil gel and a cosmetic each having good oil solubility and not containing undissolved substances due to the groups of foreign matters.

The subject oil-gelling agent comprises a dextrin fatty acid ester which is obtained by esterifying dextrin with a fatty acid chloride or a fatty acid anhydride in the presence of a pyridine derivative represented by formula I [R1 is CH3, C2H5, COOH, COOCH3, CONH2, or N(CH3)2; R2 is H or CH3] and satisfies the following characteristics 1 to 3. The characteristics 1: the average monosaccharide polymerization degree of the dextrin skeleton is 10 to 150. The characteristics 2: an average acyl group substitution degree is ≥1.0 per glucose unit. The characteristics 3: the acyl groups comprise a 12 to 22C straight chain saturated acyl group, a 4 to 26C branched acyl group, a 6 to 30C unsaturated acyl group and/or a 2 to 11C straight chain saturated acyl group, and the 12 to 22C straight chain saturated acyl group is contained in an amount of at least 50% or more in the molar ratio composition of the acyl groups.