A refrigerator comprising: a storage chamber configured to store food; a cooler configured to supply cold into the storage chamber; a first temperature sensor configured to sense a temperature within the storage chamber; a first tray assembly configured to define a portion of an ice making cell that is a space in which water is phase-changed into ice by the cold; a second tray assembly configured to define another portion of the ice making cell, wherein the another portion is disposed below the portion of the ice making cell; a water supply part configured to supply the water into the ice making cell; a second temperature sensor configured to sense a temperature of the water or the ice within the ice making cell; a heater disposed adjacent to the second tray assembly; and a controller configured to control the heater, wherein the controller controls the cooler so that the cold is supplied to the ice making cell after the second tray assembly moves to an ice making position when the water is completely supplied to the ice making cell, the controller controls the second tray assembly so that the second tray assembly moves in a reverse direction after moving to an ice separation position in a forward direction so as to take out the ice in the ice making cell when the ice is completely made in the ice making cell, the controller performs control so that a supply of the water starts after the second tray assembly moves to a water supply position in the reverse direction when the ice is completely separated, the controller controls the heater to be turned on in at least partial section while the cooler supplies the cold so that the ice is made from an upper side of the ice making cell and bubbles dissolved in the water within the ice making cell move downward from a portion, at which the ice is made, toward the water that is in a liquid state to make transparent ice, and a degree of cold transfer, which is a degree for transferring cold of the cooler, of the first tray assembly is greater than that of the second tray assembly. a storage chamber configured to store food; a cooler configured to supply cold into the storage chamber; a first temperature sensor configured to sense a temperature within the storage chamber; a first tray assembly configured to define a portion of an ice making cell that is a space in which water is phase-changed into ice by the cold; a second tray assembly configured to define another portion of the ice making cell, wherein the another portion is disposed below the portion of the ice making cell; a water supply part configured to supply the water into the ice making cell; a second temperature sensor configured to sense a temperature of the water or the ice within the ice making cell; a heater disposed adjacent to the second tray assembly; and a controller configured to control the heater, wherein the controller controls the cooler so that the cold is supplied to the ice making cell after the second tray assembly moves to an ice making position when the water is completely supplied to the ice making cell, the controller controls the second tray assembly so that the second tray assembly moves in a reverse direction after moving to an ice separation position in a forward direction so as to take out the ice in the ice making cell when the ice is completely made in the ice making cell, the controller performs control so that a supply of the water starts after the second tray assembly moves to a water supply position in the reverse direction when the ice is completely separated, the controller controls the heater to be turned on in at least partial section while the cooler supplies the cold so that the ice is made from an upper side of the ice making cell and bubbles dissolved in the water within the ice making cell move downward from a portion, at which the ice is made, toward the water that is in a liquid state to make transparent ice, and a degree of cold transfer, which is a degree for transferring cold of the cooler, of the first tray assembly is greater than that of the second tray assembly.