▎ 摘　　要

NOVELTY - Preparing hydrogel, comprises irradiating a mixed solution containing a near infrared ray sensitive material, a hydrogel precursor and a thermal initiator to near infrared rays. The near-infrared-sensitive material is graphene oxide and/or reduced graphene oxide. USE - The hydrogel is useful for injecting into body (claimed). ADVANTAGE - The hydrogel has excellent biocompatibility using near infrared rays and its operation is simple, ability to control reaction externally when used as a carrier to transport drugs and other substances, their release rate can be manipulated externally, elaborate shape and specific mechanical properties by controlling the reaction location, shape and time and exhibits high absorbance at a single wavelength. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for hydrogel composition for preparing hydrogel to inject into body, comprising near infrared ray sensitive material, a hydrogel precursor and a thermal initiator.