To produce acrylamide from acrylonitrile by use of a new enzyme, nitrile hydratase, a number of nitrile-utilizing microorganisms were screened for the enzyme activity by an intact cell system. An isobutyronitrile-utilizing bacterium, strain B23, showed the best productivity among 1 86 strains tested. The strain was identified taxonomically as Pseudomonas chlororaphis. The culture and reaction conditions for the production were studied for the strain. Under the optimum conditions, 400 grams/liter of acrylamide was produced in 7.5hr. The yield was nearly 100% with a trace amount of acrylic acid. The cell-free extract of the strain showed strong activity of nitrile hydratase toward acrylonitrile and extremely low activity of amidase toward acrylamide.