A medical fluid injector device, comprising: an injector head injecting a patient with a mixed medical fluid provided by mixing a first medical fluid and a second medical fluid; a controller unit having a monitor, screens for programming an injection condition for the mixed medical fluid displayed on the monitor, wherein the controller unit performs: a process of displaying a window on the monitor that includes a plurality of color segments arranged vertically, wherein each color segment functions as a button to set a mixture ratio between the first medical fluid and the second medical fluid, and a slider being capable of sliding vertically to change the mixture ratio; a process of receiving an input relating to an injection rate of the mixed medical fluid; a process of receiving an input relating to the mixture ratio between the first medical fluid and the second medical fluid performed by an operator, wherein the input is performed by pressing a color segment or moving the slider to select predetermined mixture ratio; a process of calculating the injection rate of the first medical fluid based on said input mixture ratio; a process of calculating the injection rate of the second medical fluid based on said input mixture ratio; and wherein the injector head injects the first medical fluid at the calculated injection rate of the first medical fluid and the second medical fluid at the calculated injection rate of the second medical fluid. an injector head injecting a patient with a mixed medical fluid provided by mixing a first medical fluid and a second medical fluid; a controller unit having a monitor, screens for programming an injection condition for the mixed medical fluid displayed on the monitor, wherein the controller unit performs: a process of displaying a window on the monitor that includes a plurality of color segments arranged vertically, wherein each color segment functions as a button to set a mixture ratio between the first medical fluid and the second medical fluid, and a slider being capable of sliding vertically to change the mixture ratio; a process of receiving an input relating to an injection rate of the mixed medical fluid; a process of receiving an input relating to the mixture ratio between the first medical fluid and the second medical fluid performed by an operator, wherein the input is performed by pressing a color segment or moving the slider to select predetermined mixture ratio; a process of calculating the injection rate of the first medical fluid based on said input mixture ratio; a process of calculating the injection rate of the second medical fluid based on said input mixture ratio; and wherein the injector head injects the first medical fluid at the calculated injection rate of the first medical fluid and the second medical fluid at the calculated injection rate of the second medical fluid. a process of displaying a window on the monitor that includes a plurality of color segments arranged vertically, wherein each color segment functions as a button to set a mixture ratio between the first medical fluid and the second medical fluid, and a slider being capable of sliding vertically to change the mixture ratio; a process of receiving an input relating to an injection rate of the mixed medical fluid; a process of receiving an input relating to the mixture ratio between the first medical fluid and the second medical fluid performed by an operator, wherein the input is performed by pressing a color segment or moving the slider to select predetermined mixture ratio; a process of calculating the injection rate of the first medical fluid based on said input mixture ratio; a process of calculating the injection rate of the second medical fluid based on said input mixture ratio;