a granulating device , and a granulating method for thermoplastic resin material , in which a screw type kneading and extruding machine for kneading , extruding and melting the thermoplastic resin material , a die holder connected to a front end portion of the screw type kneading and extruding machine , the die holder including a passage through which the melted resin material folws , a change - over valve and at least two outlets , the passage selectively connected to the outlets with the change - over valve , a first and a second dies , for forming the melted resin material into a plurality of pieces of string , connected respectively to the outlets to adapt to different ranges of viscosity of the melted resin material , and a first and a second cutter units including cutters moved respectively along extruding planes of the first and second dies to cut the string - shaped resin material into small pieces , and cooling and solidifying sections for cooling and solidifying the small pieces of thermoplastic resin material .