A method of preparing a superabsorbent polymer, the method comprising the following steps of: 1) carrying out a crosslinking polymerization of a water-soluble ethylene-based unsaturated monomer having acidic groups which are at least partially neutralized, in the presence of a foaming agent, to form a water-containing gel polymer (step 1); 2) gel-pulverizing the water-containing gel polymer (step 2); 3) drying, pulverizing, and size-sorting the gel-pulverized water-containing gel polymer to form a base polymer powder (step 3); and 4) carrying out a surface crosslinking of the base polymer powder by heat treatment in the presence of a surface crosslinking agent (step 4), wherein the gel-pulverizing step is carried out by extruding the water-containing gel polymer through a perforated panel having a plurality of holes using a screw extruder mounted inside a cylindrical pulverizer under the condition that a chopping index according to the following Equation 1 is 55 to 75: Chopping index = 2 π × N 60 × 1 A × 11 R in Equation 1, N represents the number of rotation (rpm) of a screw in the screw extruder, A represents porosity (πr 2 × n / πR 2) of the perforated panel, wherein r represents a radius (mm) of the holes formed in the perforated panel, n represents the number of holes formed in the perforated panel, and R represents a radius (mm) of the perforated panel, wherein CRC of the superabsorbent polymer is 27 g/g to 40 g/g as measured in accordance with EDANA WSP 241.3, AUP of the superabsorbent polymer is 24 g/g to 30 g/g as measured in accordance with EDANA WSP 242.3, a vortex of the superabsorbent polymer is 45 seconds or less as measured by adding 2 g of the superabsorbent polymer to 50 mL of physiological saline at 23 °C to 24 °C, and stirring with a magnetic bar (diameter of 8 mm and length of 31.8 mm) at 600 rpm, and a time taken for vortex to disappear being measured in seconds, and permeability of the superabsorbent polymer is 60 seconds or less as measured according to the description. 1) carrying out a crosslinking polymerization of a water-soluble ethylene-based unsaturated monomer having acidic groups which are at least partially neutralized, in the presence of a foaming agent, to form a water-containing gel polymer (step 1); 2) gel-pulverizing the water-containing gel polymer (step 2); 3) drying, pulverizing, and size-sorting the gel-pulverized water-containing gel polymer to form a base polymer powder (step 3); and 4) carrying out a surface crosslinking of the base polymer powder by heat treatment in the presence of a surface crosslinking agent (step 4), wherein the gel-pulverizing step is carried out by extruding the water-containing gel polymer through a perforated panel having a plurality of holes using a screw extruder mounted inside a cylindrical pulverizer under the condition that a chopping index according to the following Equation 1 is 55 to 75: Chopping index = 2 π × N 60 × 1 A × 11 R in Equation 1, N represents the number of rotation (rpm) of a screw in the screw extruder, A represents porosity (πr 2 × n / πR 2) of the perforated panel, wherein r represents a radius (mm) of the holes formed in the perforated panel, n represents the number of holes formed in the perforated panel, and R represents a radius (mm) of the perforated panel, wherein CRC of the superabsorbent polymer is 27 g/g to 40 g/g as measured in accordance with EDANA WSP 241.3, AUP of the superabsorbent polymer is 24 g/g to 30 g/g as measured in accordance with EDANA WSP 242.3, a vortex of the superabsorbent polymer is 45 seconds or less as measured by adding 2 g of the superabsorbent polymer to 50 mL of physiological saline at 23 °C to 24 °C, and stirring with a magnetic bar (diameter of 8 mm and length of 31.8 mm) at 600 rpm, and a time taken for vortex to disappear being measured in seconds, and permeability of the superabsorbent polymer is 60 seconds or less as measured according to the description. wherein the gel-pulverizing step is carried out by extruding the water-containing gel polymer through a perforated panel having a plurality of holes using a screw extruder mounted inside a cylindrical pulverizer under the condition that a chopping index according to the following Equation 1 is 55 to 75: Chopping index = 2 π × N 60 × 1 A × 11 R in Equation 1, N represents the number of rotation (rpm) of a screw in the screw extruder, A represents porosity (πr 2 × n / πR 2) of the perforated panel, wherein r represents a radius (mm) of the holes formed in the perforated panel, n represents the number of holes formed in the perforated panel, and R represents a radius (mm) of the perforated panel, wherein CRC of the superabsorbent polymer is 27 g/g to 40 g/g as measured in accordance with EDANA WSP 241.3, AUP of the superabsorbent polymer is 24 g/g to 30 g/g as measured in accordance with EDANA WSP 242.3, a vortex of the superabsorbent polymer is 45 seconds or less as measured by adding 2 g of the superabsorbent polymer to 50 mL of physiological saline at 23 °C to 24 °C, and stirring with a magnetic bar (diameter of 8 mm and length of 31.8 mm) at 600 rpm, and a time taken for vortex to disappear being measured in seconds, and permeability of the superabsorbent polymer is 60 seconds or less as measured according to the description.