Using a newly developed batch crystallizer (WWDJ-crystallizer) equipped with a slurry sprinkler named Wall Wetter and a double-deck jacket, a suppression of the solvent-mediated transformation of the metastable polymorphic crystals was attempted. Crystallization of L-glutamic acid was carried out to show an example of the suppression. The target polymorphic crystals, namely the metastable alpha-form crystals were exclusively obtained from the aqueous solution without transformation to the stable beta-form polymorph even at a temperature where the transformation could not be avoided if a conventional batch crystallizer was used. The characteristic size of crystals obtained by WWDJ-crystallizer was large and their size distribution was narrow, comparing with those obtained by a conventional crystallizer.