<;P>;PROBLEM TO BE SOLVED: To provide a food-originated and safe mitochondria fusion promotor, and an anti-obesity agent, a muscle-strengthening agent and a functional food or feed containing the same. <;P>;SOLUTION: This mitochondria fusion promotor contains a protein-decomposed material of a soybean raw material in which soybean embryo occupies &ge;30 wt.%, as an active ingredient. The protein-decomposed material which is the active ingredient of the mitochondria fusion promotor, is obtained by decomposing the soybean raw material with a protease, etc. Preferably, the mitochondria fusion promotor consisting of the protein-decomposed material having &le;3,000 molecular weight is useful as the anti-obesity agent and a visceral fat accumulation-preventing agent. <;P>;COPYRIGHT: (C)2011,JPO&INPIT