A refrigerator comprising: a body; a carbonated water tank provided at an interior of the body to produce carbonated water through mixing of water with carbon dioxide gas, the carbonated water tank provided with a carbonated water tank hole formed in a top surface thereof; coupling rods protruding from the top surface of the carbonated water tank while being formed with threads at an upper end portion thereof, a sensor unit to sense an internal state of the carbonated water tank; a plurality of lines (200, 210, 220, 230) provided to guide water, carbon dioxide gas and the carbonated water to be introduced into and discharged from the carbonated water tank; and a holding unit seated on top of the carbonated water tank to cover the carbonated water tank while enclosing the carbonated water tank hole, the holding unit having fixed thereto the plurality of lines (200, 210, 220, 230) and the sensor unit so that the sensor unit is inserted into the carbonated water tank through the carbonated water tank hole, wherein the holding unit comprises: a holding plate, to which the sensor unit is fixed; a plate support provided at a peripheral portion of the holding plate, to be supported by the carbonated water tank; fitting tubes each fixed, at one end thereof, to the holding unit while communicating, at the other end thereof, with a corresponding one of the plurality of lines (200, 210, 220, 230); and coupling holes positioned to allow a respective coupling rod to extend to allow the holding unit to be firmly fixed to the carbonated water tank by fastening nuts. a body; a carbonated water tank provided at an interior of the body to produce carbonated water through mixing of water with carbon dioxide gas, the carbonated water tank provided with a carbonated water tank hole formed in a top surface thereof; coupling rods protruding from the top surface of the carbonated water tank while being formed with threads at an upper end portion thereof, a sensor unit to sense an internal state of the carbonated water tank; a plurality of lines (200, 210, 220, 230) provided to guide water, carbon dioxide gas and the carbonated water to be introduced into and discharged from the carbonated water tank; and a holding unit seated on top of the carbonated water tank to cover the carbonated water tank while enclosing the carbonated water tank hole, the holding unit having fixed thereto the plurality of lines (200, 210, 220, 230) and the sensor unit so that the sensor unit is inserted into the carbonated water tank through the carbonated water tank hole, wherein the holding unit comprises: a holding plate, to which the sensor unit is fixed; a plate support provided at a peripheral portion of the holding plate, to be supported by the carbonated water tank; fitting tubes each fixed, at one end thereof, to the holding unit while communicating, at the other end thereof, with a corresponding one of the plurality of lines (200, 210, 220, 230); and coupling holes positioned to allow a respective coupling rod to extend to allow the holding unit to be firmly fixed to the carbonated water tank by fastening nuts. a holding plate, to which the sensor unit is fixed; a plate support provided at a peripheral portion of the holding plate, to be supported by the carbonated water tank; fitting tubes each fixed, at one end thereof, to the holding unit while communicating, at the other end thereof, with a corresponding one of the plurality of lines (200, 210, 220, 230); and coupling holes positioned to allow a respective coupling rod to extend to allow the holding unit to be firmly fixed to the carbonated water tank by fastening nuts.