Casein phosphopeptides (CPPs), which inhibit the precipitation of calcium phosphate in the intestines, were prepared as CPP-calcium phosphate complexes from casein micelles by the ultrafiltration method. The prepared CPPs hardly contained any other peptides, so there was no need to treat with active carbon to remove the bitter peptides. The sum of alpha s1-CN-5P(f59-79) and beta-CN-4P(f1-25) comprised 60% of the CPP composition by an analysis of the elution pattern from a Q-Sepharose FF column. The content of alpha s1-CN-5P(f59-79), which has high retention ability for calcium phosphate, was the highest in the CPPs.