Disclosed are a device and a method for manufacturing a natural gas hydrate. Provided is the device for manufacturing a natural gas hydrate comprising: an ice slurry generation unit for preparing ice slurry having 13-20% of ice at normal pressure; a first pipe, having one end connected to the ice slurry generation unit for withdrawing the ice slurry from the ice slurry generation unit, and in which a high-pressure pump for increasing pressure on the ice slurry is interposed; a hydrate preparation reactor, which is connected to the other end of the first pipe so as to receive the pressurized ice slurry, and to which natural gas is supplied and mixed, for generating natural gas hydrate slurry; a second pipe, having one end connected to the hydrate preparation reactor, for withdrawing the natural gas hydrate slurry; and a dehydrating portion, which is connected to the other end of the second pipe, for dehydrating the natural gas hydrate slurry.