<p>Provided is a method for producing acrylic acid which comprises subjecting a composition containing propionaldehyde to a gas-phase oxidative dehydrogenation reaction using a solid catalyst that comprises Mo and V as the essential components to thereby produced acrylic acid. The acrylic acid thus obtained is preferably purified via a crystallization step and then a monomer component containing the purified acrylic acid is polymerize to thereby give a hydrophilic resin such as a water-absorbing resin or a water-soluble resin.</p>
