Provided are a phosphorylated peptide having the effect of inhibiting hard tissue and/or ectopic calcification using the active sites for a calcification inhibiting effect of MEPE-derived ASARM peptide, a hard tissue and/or ectopic calcification inhibitor, antibody having a hard tissue and/or ectopic calcification-promoting effect, and a hard tissue and/or ectopic calcification promoter. The phosphorylated peptide is characterized in that the peptide has the entire or partial amino acid sequence of MEPE-derived ASARM peptide, at least two of the amino acid residues in the amino acid sequence are phosphorylated serine, and the peptide has a hard tissue and/or ectopic calcification-inhibiting effect. The antibody is characterized in recognizing phosphorylated serine, which is the active center of the phosphorylated peptide.