NOVELTY - Production of polyacrylic acid comprises acrylic acid production process including catalytically oxidizing propylene and/or propane in gaseous phase and polyacrylic acid production process including utilizing steam recovered in acrylic acid production process to purify polyacrylic acid from acrylic acid aqueous solution or acrylic acid.    USE - For producing polyacrylic acid, e.g. water-soluble polyacrylic acid (salt) or water-absorbent resin.    ADVANTAGE - The inventive method efficiently utilizes steam recovered in acrylic acid production for production of polyacrylic acid, thus suppressing loss of steam.    DETAILED DESCRIPTION - Production of polyacrylic acid comprises acrylic acid production process including catalytically oxidizing propylene and/or propane in gaseous phase, absorbing reaction product in a solvent, and purifying acrylic acid from acrylic acid aqueous solution; and polyacrylic acid production process including utilizing steam recovered in acrylic acid production process to purify polyacrylic acid from acrylic acid aqueous solution or acrylic acid.    An INDEPENDENT CLAIM is also included for a polyacrylic acid production apparatus comprising an evaporator (2) for gasifying propylene and/or propane; a catalytic oxidation device (7) for catalytically oxidizing the gasified propylene and/or propane in a gaseous phase; an absorption column (11) for absorbing reaction product in a solvent; a purification column (24) for purifying acrylic acid by distillation; a neutralizing device (34) for neutralizing acrylic acid aqueous solution and acrylic acid before, during, or after polymerization; a polymerization device; a drying device (36) for drying polymerized substance; and a pipeline for feeding heat medium obtained in a heat recovering device into the acrylic acid production apparatus.    DESCRIPTION OF DRAWING(S) - The figure is a schematic drawing showing an acrylic acid production process.    Evaporator (2)    Catalytic oxidation device (7)    Absorption column (11)    Purification column (24)    Neutralizing device (34)    Drying device (36)