A thermometer comprising: a main body having a first body including a first region and a second region and a second body mounted on the first body, the main body extending in a first direction; a rubber cap surrounding the second region and formed to be inserted into an ear; a temperature sensor disposed to be directed to the first direction in the second region and having a specific temperature sensing range of a specific angle based on the first direction; first and second circuit boards (1314, 1316) electrically connected to the temperature sensor and disposed in the second region in a second direction intersecting the first direction, wherein the first body and the rubber cap include first and second holes (h1, h2) for exposing the temperature sensor, and the first body has one end (1110") cut along the second direction, and the second body is mounted on the one end (1110") of the first body, characterized in that the first region further comprises: a first module coupled to the first body and disposed at the one end (1110") of the first body in the first direction, wherein the first and second circuit boards (1314, 1316) are disposed on a first surface of the first module so that the first and second circuit boards (1314, 1316) overlap in at least one area with each other; a second module mounted on the first surface of the first module and formed to surround a peripheral region of the first and second circuit boards (1314, 1316); and a third module coupled to the second module and supporting the temperature sensor (1311, 1331), in that a side wall portion is formed on a second surface of the first module so as to surround a battery unit, and in that the second module includes a sidewall portion formed so as to surround the first and second circuit boards (1314, 1316) and a supporting portion protruding from the side wall portion of the second module and supporting between the first and second circuit boards (1314, 1316). a main body having a first body including a first region and a second region and a second body mounted on the first body, the main body extending in a first direction; a rubber cap surrounding the second region and formed to be inserted into an ear; a temperature sensor disposed to be directed to the first direction in the second region and having a specific temperature sensing range of a specific angle based on the first direction; first and second circuit boards (1314, 1316) electrically connected to the temperature sensor and disposed in the second region in a second direction intersecting the first direction, wherein the first body and the rubber cap include first and second holes (h1, h2) for exposing the temperature sensor, and the first body has one end (1110") cut along the second direction, and the second body is mounted on the one end (1110") of the first body, characterized in that the first region further comprises: a first module coupled to the first body and disposed at the one end (1110") of the first body in the first direction, wherein the first and second circuit boards (1314, 1316) are disposed on a first surface of the first module so that the first and second circuit boards (1314, 1316) overlap in at least one area with each other; a second module mounted on the first surface of the first module and formed to surround a peripheral region of the first and second circuit boards (1314, 1316); and a third module coupled to the second module and supporting the temperature sensor (1311, 1331), a first module coupled to the first body and disposed at the one end (1110") of the first body in the first direction, wherein the first and second circuit boards (1314, 1316) are disposed on a first surface of the first module so that the first and second circuit boards (1314, 1316) overlap in at least one area with each other; a second module mounted on the first surface of the first module and formed to surround a peripheral region of the first and second circuit boards (1314, 1316); and a third module coupled to the second module and supporting the temperature sensor (1311, 1331), in that a side wall portion is formed on a second surface of the first module so as to surround a battery unit, and in that the second module includes a sidewall portion formed so as to surround the first and second circuit boards (1314, 1316) and a supporting portion protruding from the side wall portion of the second module and supporting between the first and second circuit boards (1314, 1316).