There is provided a method of manufacturing a protein array or peptide array suitable for an efficient screening of a functional protein or functional peptide. The method of manufacturing a protein array or peptide array includes the steps of: (a) preparing a nucleic acid immobilized on a solid support and a cell-free synthesis system in a reactor, in which a reactor array includes the reactor having a specific aperture shape and a protein capture molecule or a peptide capture molecule provided on at least a portion of wall surface and bottom surface in the reactor; and (c) synthesizing a protein or peptide from the nucleic acid using the cell-free synthesis system and immobilizing the protein or peptide in the reactor.