To provide an analyzer configured to enable to determine whether or not phosphoric acid is bound to a peptide or protein in a short time according to a simple procedure, and to provide a program for use in the analyzer, and a recording medium for storing the program. A spectrum of a peptide or protein in the infrared region is determined so as to specify the type of a phosphorylated amino acid in the peptide or protein based on a peak position in a region of 1,000 to 1,100 [cm.sup.-1] of the spectrum.