A refrigerator comprising: a storage chamber configured to store food; a cooler configured to supply cold air 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 air, a second tray assembly configured to define another portion of the ice making cell, the second tray assembly being connected to a driver to contact the first tray assembly in an ice making process and to be spaced apart from the first tray assembly in an ice separation process; 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 and the driver, wherein the controller is configured to control the cooler so that the cold air 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 is configured to control 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 is configured to control the second tray assembly 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 is configured to control the heater to be turned on in at least partial section while the cooler supplies the cold air so that bubbles dissolved in the water within the ice making cell moves from a portion, at which the ice is made, toward the water that is in a liquid state to make transparent ice, the first tray assembly comprises a first tray, and the second tray assembly comprises a second tray, the second tray is disposed closer to the heater than the first tray, and the second tray comprises a first portion that defines at least a portion of the ice making cell and a second portion extending from a predetermined point of the first portion. a storage chamber configured to store food; a cooler configured to supply cold air 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 air, a second tray assembly configured to define another portion of the ice making cell, the second tray assembly being connected to a driver to contact the first tray assembly in an ice making process and to be spaced apart from the first tray assembly in an ice separation process; 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 and the driver, wherein the controller is configured to control the cooler so that the cold air 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 is configured to control 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 is configured to control the second tray assembly 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 is configured to control the heater to be turned on in at least partial section while the cooler supplies the cold air so that bubbles dissolved in the water within the ice making cell moves from a portion, at which the ice is made, toward the water that is in a liquid state to make transparent ice, the first tray assembly comprises a first tray, and the second tray assembly comprises a second tray, the second tray is disposed closer to the heater than the first tray, and the second tray comprises a first portion that defines at least a portion of the ice making cell and a second portion extending from a predetermined point of the first portion.