A photopolymerizable composition which is highly sensitive to light not only in the visible region but in long-wavelength regions including the near infrared region, is not sensitive to light in the ultraviolet region, and has excellent handling efficiency under day light fluorescent lamps, and a photopolymerizable lithographic printing plate, are presented. A photopolymerizable composition comprising the following components (A), (B) and (C), and a photopolymerizable lithographic printing plate comprising a support and, formed on a surface thereof, a layer of the photopolymerizable composition: (A) an ethylenically unsaturated compound; (B) a dye which has, as a basic structure, a structure having hetero atoms connected via a polymethine chain and which is selected from the group consisting of the following (B-1), (B-2), (B-3) and (B-4): (B-1) a dye having, on a polymethine chain, a substituent containing a chain ether bond which forms an oxonium cation or a chain thioether bond which forms a sulfonium cation, upon resonance in the dye molecule, (B-2) a dye having, on a polymethine chain, two substituents forming a cyclic ether bond which forms an oxonium cation or a cyclic thioether bond which forms a sulfonium cation, upon resonance in the dye molecule, (B-3) a dye having, on a polymethine chain, a substituent containing an amino-vinyl bond which forms an aminium cation upon resonance in the dye molecule, and (B-4) a dye having, on a polymethine chain or other basic structure, a substituent containing an acid anion group, its ester group or a base; and (C) a photopolymerization initiator.