Provided is a novel improved nitrile hydratase with improved resistance to amide compounds under high temperatures. Specifically provided is a nitrile hydratase having at least one amino acid mutation selected from (a) to (d) below, in the amino acid sequence expressed in SEQ ID NO:50 (X1 to X27 represent independent arbitrarily-defined amino acid residuals). (a) X1 is valine or glycine (b) X9 is valine or threonine (c) X23 is an amino acid selected from a group consisting of isoleucine, leucine, methionine and threonine, (d) X24 is leucine.