A stretchable adhesive film comprising: a substrate layer comprising an elastomer; and a first adhesive layer provided on one surface of the substrate layer, wherein the stretchable adhesive film satisfies the following Equation 1: 0.95 ≤ a 2 / a 1 ≤ 1 in Equation 1, a1 is a stress value of the stretchable adhesive film at X1 under 25±2°C and 50±5% RH (relative humidity), wherein both ends of the stretchable adhesive film are fixed in a length direction so that the width becomes 25 mm and the length becomes 165 mm under 25±2°C and 50±5% RH (relative humidity), and the stretchable adhesive film is elongated to X1 at a rate of 100 mm/min using a texture analyzer, and then recovered to the initial state in the opposite direction at a rate of 100 mm/min; a2 is a stress value at X1 after evaluating elongation/recovery on the stretchable adhesive film 10,000 times with a 20% strain under 25±2°C and 50±5% RH (relative humidity), wherein both ends of the stretchable adhesive film are fixed in a length direction so that the width becomes 25 mm and the length becomes 165 mm under 25±2°C and 50±5% RH (relative humidity), elongation and recovery are applied 10,000 times up to a 20% strain in a length direction at a rate of once per second, and after that, the stretchable adhesive film is elongated to X1 at a rate of 100 mm/min using a texture analyzer, and then recovered to the initial state in the opposite direction at a rate of 100 mm/min; X1 is a strain value (%) applied to the stretchable adhesive film; the strain means an elongational strain, wherein the elongational strain is defined by the following Equation 2 when an initial length is defined by L0, and an elongated length is defined by L: L − L 0 / L 0 × 100; and X1 is 20, wherein the substrate layer has a thickness of greater than or equal to 60 μm and less than or equal to 150 μm, wherein the elastomer comprises silicone rubber, and wherein the silicone rubber comprises one or more selected from the group consisting of methyl silicone, vinyl-methyl-silicone, phenyl-vinyl-methyl-silicone (PVMQ) and fluorovinyl-methyl-silicone (FVMQ). a substrate layer comprising an elastomer; and a first adhesive layer provided on one surface of the substrate layer, wherein the stretchable adhesive film satisfies the following Equation 1: 0.95 ≤ a 2 / a 1 ≤ 1 in Equation 1, a1 is a stress value of the stretchable adhesive film at X1 under 25±2°C and 50±5% RH (relative humidity), wherein both ends of the stretchable adhesive film are fixed in a length direction so that the width becomes 25 mm and the length becomes 165 mm under 25±2°C and 50±5% RH (relative humidity), and the stretchable adhesive film is elongated to X1 at a rate of 100 mm/min using a texture analyzer, and then recovered to the initial state in the opposite direction at a rate of 100 mm/min; a2 is a stress value at X1 after evaluating elongation/recovery on the stretchable adhesive film 10,000 times with a 20% strain under 25±2°C and 50±5% RH (relative humidity), wherein both ends of the stretchable adhesive film are fixed in a length direction so that the width becomes 25 mm and the length becomes 165 mm under 25±2°C and 50±5% RH (relative humidity), elongation and recovery are applied 10,000 times up to a 20% strain in a length direction at a rate of once per second, and after that, the stretchable adhesive film is elongated to X1 at a rate of 100 mm/min using a texture analyzer, and then recovered to the initial state in the opposite direction at a rate of 100 mm/min; X1 is a strain value (%) applied to the stretchable adhesive film; the strain means an elongational strain, wherein the elongational strain is defined by the following Equation 2 when an initial length is defined by L0, and an elongated length is defined by L: L − L 0 / L 0 × 100; and X1 is 20, wherein the substrate layer has a thickness of greater than or equal to 60 μm and less than or equal to 150 μm, wherein the elastomer comprises silicone rubber, and wherein the silicone rubber comprises one or more selected from the group consisting of methyl silicone, vinyl-methyl-silicone, phenyl-vinyl-methyl-silicone (PVMQ) and fluorovinyl-methyl-silicone (FVMQ).