more preferred egg yolk protein hydrolysate is one obtained through fractionation using an ultrafiltration membrane with a molecular weight cut off of 1 000 wherein the molecular weight distribution of the hydrolysate as determined by gel filtration chromatography is such that the peak area percentage for a molecular weight range of about 500 to about 20 000 is about 85 or more preferably about 90 or more of the total area of all the peaks of proteins peptides and amino acids the egg yolk protein hydrolysate prepared as above has hair regrowth promoting effect hair growth promoting effect hair nourishing effect anti alopecia effect etc the egg yolk protein hydrolysate is thus suitable as an active ingredient of hair regrowth promoters hair growth promoters hair nourishers anti alopecia agents etc thus the hair regrowth promoter of the present invention may also be referred to as a hair growth promoter a hair nourisher or an anti alopecia agent the amount of the egg yolk protein hydrolysate contained in the hair regrowth promoter of the present invention is not particularly limited but is preferably about 0 05 to about 50 by mass more preferably about 0 1 to about 25 by mass the daily dose of the egg yolk protein hydrolysate varies depending on the subject but in cases where the subject is for example a human adult the daily dose is typically about 0 05 to about 2000 mg day and is preferably about 0 1 to about 1000 mg day the hair regrowth promoter of the present invention promotes the production of a growth factor in hair follicle dermal papilla cells the growth factor.