A patch for attaching to teeth or a surrounding part of teeth, which comprises: a drug layer including a drug component; and a backing layer which is positioned on one side of the drug layer and whose tensile strength is reduced by 50% or more by absorbing moisture, compared to before moisture absorption, wherein the patch for attaching to teeth or a surrounding part of teeth is degradable and detachable by tooth brushing, the tensile strength of the backing layer of the patch, which is measured in a state that moisture is sufficiently absorbed so that the moisture content rate does not change for 10 sec, and measured at an environment of temperature of 25°C using Zwick, DE/1494 universal testing machine at a rate of 0.1 mm/s, is reduced by 50% or more, compared to before moisture absorption, the backing layer includes both of: at least one water-insoluble polymer, which is ethyl cellulose; and at least one water-soluble polymer selected from the group consisting of polyalkyl vinyl ether-maleic acid copolymer (PVM/MA copolymer), polyvinyl alcohol, polyacrylic acid, Poloxamer 407, polyethyleneoxide (Polyox), polyvinyl pyrrolidone-vinyl acetate copolymer (PVP/VA copolymer), polyvinyl pyrrolidone (PVP), polyquaternium-11, polyquaternium-39, carboxypolymethylene (Carbomer), hydroxypropyl methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, gelatin and sodium alginate, and the backing layer further comprises at least one plasticizer selected from the group consisting of castor oil and hydrogenated castor oil. a drug layer including a drug component; and a backing layer which is positioned on one side of the drug layer and whose tensile strength is reduced by 50% or more by absorbing moisture, compared to before moisture absorption, wherein the patch for attaching to teeth or a surrounding part of teeth is degradable and detachable by tooth brushing, the tensile strength of the backing layer of the patch, which is measured in a state that moisture is sufficiently absorbed so that the moisture content rate does not change for 10 sec, and measured at an environment of temperature of 25°C using Zwick, DE/1494 universal testing machine at a rate of 0.1 mm/s, is reduced by 50% or more, compared to before moisture absorption, the backing layer includes both of: at least one water-insoluble polymer, which is ethyl cellulose; and at least one water-soluble polymer selected from the group consisting of polyalkyl vinyl ether-maleic acid copolymer (PVM/MA copolymer), polyvinyl alcohol, polyacrylic acid, Poloxamer 407, polyethyleneoxide (Polyox), polyvinyl pyrrolidone-vinyl acetate copolymer (PVP/VA copolymer), polyvinyl pyrrolidone (PVP), polyquaternium-11, polyquaternium-39, carboxypolymethylene (Carbomer), hydroxypropyl methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, gelatin and sodium alginate, and the backing layer further comprises at least one plasticizer selected from the group consisting of castor oil and hydrogenated castor oil. at least one water-insoluble polymer, which is ethyl cellulose; and at least one water-soluble polymer selected from the group consisting of polyalkyl vinyl ether-maleic acid copolymer (PVM/MA copolymer), polyvinyl alcohol, polyacrylic acid, Poloxamer 407, polyethyleneoxide (Polyox), polyvinyl pyrrolidone-vinyl acetate copolymer (PVP/VA copolymer), polyvinyl pyrrolidone (PVP), polyquaternium-11, polyquaternium-39, carboxypolymethylene (Carbomer), hydroxypropyl methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, gelatin and sodium alginate, and the backing layer further comprises at least one plasticizer selected from the group consisting of castor oil and hydrogenated castor oil. <EOS>