[Problem] To provide a useful dipeptide-containing composition derived from dried bonito flakes and the like, having an angiotensin-converting-enzyme inhibiting activity that imparts a blood pressure reducing function. [Solution] A composition containing a dipeptide derived from a fish meat protein having an angiotensin-converting-enzyme inhibiting activity. The composition is characterised by containing: at least one type of dipeptide selected from the group consisting of a dipeptide consisting of a tryptophan-leucine amino acid sequence, a dipeptide consisting of a leucine-tryptophan amino acid sequence, a dipeptide consisting of a tryptophan-isoleucine amino acid sequence, a dipeptide consisting of a valine-triptophan sequence, a dipeptide consisting of a tryptophan-tyrosine sequence, a dipeptide consisting of a tryptophan-methonine sequence, a dipeptide consisting of a serin-triptophan sequence, and a dipeptide consisting of an asparagine-triptophan sequence and/or an acid addition salt of said dipeptide(s).
