A freeze-dried body for a filler comprising hydrophilic surface-treated biodegradable polymer microparticle and a biocompatible carrier, wherein the hydrophilic surface-treated biodegradable polymer microparticle has an average particle diameter (D 50) of 20 to 50 μm and is polydioxanone which has a carboxyl group on the surface thereof, wherein the hydrophilic surface-treated biodegradable polymer microparticle is a plasma surface-treated product or a base surface-treated product using discharge of the biodegradable polymer microparticle, wherein the content of the biocompatible carrier is 1 to 5 parts by weight based on 100 parts by weight of the freeze-dried body, wherein the biocompatible carrier is sodium carboxymethyl cellulose, and the moisture content in the freeze-dried body is 0.5 to 1.0% by weight, wherein a powder-water contact angle value to the hydrophilic surface-treated biodegradable polymer microparticle is 35.1 to 35.7°, wherein the base surface-treated product of the biodegradable polymer microparticle is a product obtained through the operations of: adding 0.1 to 5% by weight of a sodium hydroxide solution to the biodegradable polymer microparticle for a filler, and stirring it for 30 seconds to 300 seconds; and washing and vacuum-drying the product obtained through the stirring operation, wherein the content of sodium hydroxide is 1 to 5 parts by weight based on 100 parts by weight of the biodegradable polymer microparticle for a filler, and wherein the plasma surface-treated product is a product obtained through the operations of: applying voltage to the biodegradable polymer microparticle for a filler to induce discharge; and performing a discharge treatment of the biodegradable polymer microparticle, wherein the discharge treatment of the biodegradable polymer microparticle is performed through the operations of: injecting 400 to 600 mL/min of air in a plasma reaction device; applying 300 Hz to 500 Hz of alternating current to an electrode to which a power supply unit is connected to obtain plasma-treated air; and making the plasma-treated air come into contact with the biodegradable polymer microparticle. wherein the hydrophilic surface-treated biodegradable polymer microparticle is a plasma surface-treated product or a base surface-treated product using discharge of the biodegradable polymer microparticle, wherein the content of the biocompatible carrier is 1 to 5 parts by weight based on 100 parts by weight of the freeze-dried body, wherein the biocompatible carrier is sodium carboxymethyl cellulose, and the moisture content in the freeze-dried body is 0.5 to 1.0% by weight, wherein a powder-water contact angle value to the hydrophilic surface-treated biodegradable polymer microparticle is 35.1 to 35.7°, wherein the base surface-treated product of the biodegradable polymer microparticle is a product obtained through the operations of: adding 0.1 to 5% by weight of a sodium hydroxide solution to the biodegradable polymer microparticle for a filler, and stirring it for 30 seconds to 300 seconds; and washing and vacuum-drying the product obtained through the stirring operation, wherein the content of sodium hydroxide is 1 to 5 parts by weight based on 100 parts by weight of the biodegradable polymer microparticle for a filler, and wherein the plasma surface-treated product is a product obtained through the operations of: applying voltage to the biodegradable polymer microparticle for a filler to induce discharge; and performing a discharge treatment of the biodegradable polymer microparticle, wherein the discharge treatment of the biodegradable polymer microparticle is performed through the operations of: injecting 400 to 600 mL/min of air in a plasma reaction device; applying 300 Hz to 500 Hz of alternating current to an electrode to which a power supply unit is connected to obtain plasma-treated air; and making the plasma-treated air come into contact with the biodegradable polymer microparticle.