A core body temperature measurement device comprising: a body configured to be fixed to an ear canal of a user; and an operation unit (300, 301) combined with a front side of the body, and having a sensor part configured to be exposed to the ear canal or to be concealed inside the operation unit (300, 301); the operation unit (300, 301) further comprising: a cover frame configured to form an outer shape of the operation unit (300, 301), and positioned to face a skin surface of the ear canal; a rotation part disposed inside of the cover frame, and configured to receive a driving force to be rotated; first and second moving parts combined with opposing sides of the rotation part respectively, and configured to move along an inner side of the cover frame when the rotation part is rotated; and a cover part fixed to the first moving part, and configured to open or close an opening portion of the cover frame through which the sensor part is exposed; wherein the sensor part is configured to measure a core body temperature of user when it is exposed to the ear canal; wherein the sensor part is fixed to the second moving part; wherein the sensor part is configured to be exposed outside of the cover frame along a lateral direction toward the skin of the ear canal, to measure a core body temperature of the user as the second moving part moves and the cover part opens the opening portion; wherein the sensor part is configured to be concealed inside of the cover frame along the lateral direction away from the skin of the ear canal, as the second moving part moves and the cover part closes the opening portion. a body configured to be fixed to an ear canal of a user; and an operation unit (300, 301) combined with a front side of the body, and having a sensor part configured to be exposed to the ear canal or to be concealed inside the operation unit (300, 301); the operation unit (300, 301) further comprising: a cover frame configured to form an outer shape of the operation unit (300, 301), and positioned to face a skin surface of the ear canal; a rotation part disposed inside of the cover frame, and configured to receive a driving force to be rotated; first and second moving parts combined with opposing sides of the rotation part respectively, and configured to move along an inner side of the cover frame when the rotation part is rotated; and a cover part fixed to the first moving part, and configured to open or close an opening portion of the cover frame through which the sensor part is exposed; a cover frame configured to form an outer shape of the operation unit (300, 301), and positioned to face a skin surface of the ear canal; a rotation part disposed inside of the cover frame, and configured to receive a driving force to be rotated; first and second moving parts combined with opposing sides of the rotation part respectively, and configured to move along an inner side of the cover frame when the rotation part is rotated; and a cover part fixed to the first moving part, and configured to open or close an opening portion of the cover frame through which the sensor part is exposed; wherein the sensor part is configured to measure a core body temperature of user when it is exposed to the ear canal; wherein the sensor part is fixed to the second moving part; wherein the sensor part is configured to be exposed outside of the cover frame along a lateral direction toward the skin of the ear canal, to measure a core body temperature of the user as the second moving part moves and the cover part opens the opening portion; wherein the sensor part is configured to be concealed inside of the cover frame along the lateral direction away from the skin of the ear canal, as the second moving part moves and the cover part closes the opening portion.