Provided is an oil or fat composition for promoting insulin secretion, the composition being very safe, devoid of concerns of side effects even when ingested continuously, and effective in preventing diabetes and other uses. This oil or fat composition for promoting insulin secretion is characterized in containing a triacylglycerol and an emulsifier as active ingredients, the triacylglycerol having one or two medium-chain fatty acid residues in a molecule and containing, as constituent fatty acids, a C6-12 medium-chain fatty acid and a C16-24 long-chain fatty acid and the emulsifier being at least one selected from the group consisting of a phospholipid, a sucrose fatty acid ester, a polyglycerol fatty acid ester, and a glycerol mono-fatty acid ester.
