A sheet-like application member having an application surface to be applied to a subject, the application member comprising: a first region having an attachment surface to which a medical device (20, 20a-20h) can be attached, the attachment surface being different from the application surface; a second region having stronger adhesion in the application surface than the first region and provided around the first region; and a tear portion formed as a linear portion that is capable of being torn, said tear portion is either formed inside the first region capable of tearing a portion within the first region to separate said portion within the first region from a portion of the first region remaining and the second region or provided between the first region and the second region capable of tearing apart the first region and the second region to separate the first region from the second region, wherein the attachment surface side of the application member is an upper side and the application surface side of the application member is a lower side, wherein the angle (θ) between the skin of the subject and the application surface reaches a predetermined angle when a tongue portion (35, 38, 43), which is a portion of the first region or the second region formed by a slit (34, 37, 41, 42), when a protrusion in the second region protruding in a direction opposite the first region on at least any one side (32b, 32c, 33a) or when a protrusion of the first region protruding toward the second region on at least any one side (32b, 32c, 33a) is lifted, to reduce the burden on the skin when removing an entire medical instrument from the skin, wherein the medical instrument comprises the sheet-like application member and the medical device (20, 20a-20h). a first region having an attachment surface to which a medical device (20, 20a-20h) can be attached, the attachment surface being different from the application surface; a second region having stronger adhesion in the application surface than the first region and provided around the first region; and a tear portion formed as a linear portion that is capable of being torn, said tear portion is either formed inside the first region capable of tearing a portion within the first region to separate said portion within the first region from a portion of the first region remaining and the second region or provided between the first region and the second region capable of tearing apart the first region and the second region to separate the first region from the second region, wherein the attachment surface side of the application member is an upper side and the application surface side of the application member is a lower side, wherein the angle (θ) between the skin of the subject and the application surface reaches a predetermined angle when a tongue portion (35, 38, 43), which is a portion of the first region or the second region formed by a slit (34, 37, 41, 42), when a protrusion in the second region protruding in a direction opposite the first region on at least any one side (32b, 32c, 33a) or when a protrusion of the first region protruding toward the second region on at least any one side (32b, 32c, 33a) is lifted, to reduce the burden on the skin when removing an entire medical instrument from the skin, wherein the medical instrument comprises the sheet-like application member and the medical device (20, 20a-20h).