A flexographic printing original plate, comprising: a support; and a photosensitive resin composition layer stacked on the support, wherein the photosensitive resin composition layer contains: a thermoplastic elastomer (a), a photopolymerizable unsaturated monomer (b), a photopolymerization initiator (c), and a plasticizer (d), the thermoplastic elastomer (a) is a block copolymer that has a polymer block (A) principally containing at least one vinyl aromatic monomer unit, and a polymer block (B) principally containing at least one conjugated diene monomer unit, and that is represented by either of the following general formulas (I) and (II), the thermoplastic elastomer (a) has a weight average molecular weight of 100,000 or more and 200,000 or less, a content of a vinyl aromatic monomer unit in the thermoplastic elastomer (a) is 25.0% by mass or more, a content of vinyl bond based on a conjugated diene monomer unit in the thermoplastic elastomer (a) is 12.0% by mass or less, the thermoplastic elastomer (a) is less than 50 parts by mass based on 100 parts by mass of the photosensitive resin composition, the plasticizer (d) contains polybutadiene containing 70.0% by mass or more of cis-form, and a content of vinyl bond based on a conjugated diene monomer unit in the plasticizer (d) is less than 5.0% by mass: (A-B) n (I) (A-B) n X (II) wherein A represents the polymer block (A), B represents the polymer block (B), X represents a residue of a coupling agent or a residue of a polymerization initiator, and n represents an integer of 1 to 2. a support; and a photosensitive resin composition layer stacked on the support, wherein the photosensitive resin composition layer contains: a thermoplastic elastomer (a), a photopolymerizable unsaturated monomer (b), a photopolymerization initiator (c), and a plasticizer (d), a thermoplastic elastomer (a), a photopolymerizable unsaturated monomer (b), a photopolymerization initiator (c), and a plasticizer (d), the thermoplastic elastomer (a) is a block copolymer that has a polymer block (A) principally containing at least one vinyl aromatic monomer unit, and a polymer block (B) principally containing at least one conjugated diene monomer unit, and that is represented by either of the following general formulas (I) and (II), the thermoplastic elastomer (a) has a weight average molecular weight of 100,000 or more and 200,000 or less, a content of a vinyl aromatic monomer unit in the thermoplastic elastomer (a) is 25.0% by mass or more, a content of vinyl bond based on a conjugated diene monomer unit in the thermoplastic elastomer (a) is 12.0% by mass or less, the thermoplastic elastomer (a) is less than 50 parts by mass based on 100 parts by mass of the photosensitive resin composition, the plasticizer (d) contains polybutadiene containing 70.0% by mass or more of cis-form, and a content of vinyl bond based on a conjugated diene monomer unit in the plasticizer (d) is less than 5.0% by mass: (A-B) n (I) (A-B) n X (II) wherein A represents the polymer block (A), B represents the polymer block (B), X represents a residue of a coupling agent or a residue of a polymerization initiator, and n represents an integer of 1 to 2. <EOS>