A color temperature adjusting device includes a display unit that displays a first pointer indicating default values of chromaticity x, y and a second pointer indicating an adjustment value of the chromaticity x, y within a frame in a corresponding manner to scales of the x coordinate and the y coordinate marked on the frame, an operating unit that is used to change the x coordinate and/or the y coordinate of the second pointer, and a control unit that sends out the adjustment value indicated by the second pointer by an operation of the operating unit, to the monitor through a communication processing unit, and in a case where the monitor changes the color temperature, receives the values of the chromaticity x, y from the monitor through the communication processing unit so as to reflect and display the values of the chromaticity x, y on the display unit.