A single sheet of a clothlike macromolecule (atomic cloth; 4 Angstrom thick) comprising the columns of polydiacetylene and polyacetylene chains alternately crosslinked to the rows of alkyl chains was prepared by the photopolymerization of 1,15,17,31-dotriacontatetrayne molecules laid flat in a monolayer, This process was monitored by Penning ionization electron spectroscopy.