In a die plate having a hardened surface for sliding a knife, a plurality of WC alloy plates 1b are diffusion-bonded to a base metal 2b, whereby the hardened surface h is formed. A plurality of nozzle holes 4a, 4a . . . are formed on each of the WC alloy plates 1b. Each of the WC alloy plates 1b is formed into a shape having a thickness of 2.5 mm or more and two adjacent edges 20 mm or more in length, wherein each edge is 200 mm or less in length. The die plate has high freedom in an arrangement of nozzle holes to enable a close arrangement of a number of nozzle holes, has an extended life with hardly causing dropping-off of a member constituting a hardened surface, and can be produced with a minimized number of processes.