A transponder which comprises: an IC inlet; a first base material which is flexible; an antenna sheet which is provided above one surface of the first base material, the antenna sheet comprising an antenna coil and having a first opening, the antenna sheet being included in the IC inlet; an IC module provided on said one surface of the first base material, the IC module being connected to the antenna coil, at least a part of the IC module being provided in the first opening, the IC module being included in the IC inlet; and a second base material which has a second opening in which a part of the IC module is provided characterized in that the transponder further comprises: a sealing resin having a first portion which fills a first space in the second opening, the first space not including a second space at which the part of the IC module is provided; wherein the sealing resin has a second portion which fills a third space between a first area and a second area, the first area being on part of one surface of the second base material surrounding the second opening, and the second area being on part of one surface of the antenna sheet, wherein the first and second portions of the sealing resin are formed in a single piece, the first area is the same as the second area when seen along an axis which is perpendicular to the one surface of the second base material, and a third area is included in the first area when seen along the axis which is perpendicular to the one surface of the second base material, the third area being a part of the one surface of the first base material, the third area being an area on which the IC module is provided. an IC inlet; a first base material which is flexible; an antenna sheet which is provided above one surface of the first base material, the antenna sheet comprising an antenna coil and having a first opening, the antenna sheet being included in the IC inlet; an IC module provided on said one surface of the first base material, the IC module being connected to the antenna coil, at least a part of the IC module being provided in the first opening, the IC module being included in the IC inlet; and a second base material which has a second opening in which a part of the IC module is provided the transponder further comprises: a sealing resin having a first portion which fills a first space in the second opening, the first space not including a second space at which the part of the IC module is provided; wherein the sealing resin has a second portion which fills a third space between a first area and a second area, the first area being on part of one surface of the second base material surrounding the second opening, and the second area being on part of one surface of the antenna sheet, wherein the first and second portions of the sealing resin are formed in a single piece, the first area is the same as the second area when seen along an axis which is perpendicular to the one surface of the second base material, and a third area is included in the first area when seen along the axis which is perpendicular to the one surface of the second base material, the third area being a part of the one surface of the first base material, the third area being an area on which the IC module is provided. a sealing resin having a first portion which fills a first space in the second opening, the first space not including a second space at which the part of the IC module is provided; wherein the sealing resin has a second portion which fills a third space between a first area and a second area, the first area being on part of one surface of the second base material surrounding the second opening, and the second area being on part of one surface of the antenna sheet, wherein the first and second portions of the sealing resin are formed in a single piece, the first area is the same as the second area when seen along an axis which is perpendicular to the one surface of the second base material, and a third area is included in the first area when seen along the axis which is perpendicular to the one surface of the second base material, the third area being a part of the one surface of the first base material, the third area being an area on which the IC module is provided.