A medical fluid injector device capable of injecting a patient with a mixed medical fluid and simply setting injection conditions for the mixed medical fluid. A medical fluid injector includes an injector head injecting a diluted contrast medium into a patient and a controller unit. The controller unit receives an input relating to an injection rate of the diluted medical fluid, receives an input relating to a mixture ratio by an operator, calculates an injection rate of a contrast medium based on the mixture ratio, and calculates an injection rate of physiological saline based on the mixture ratio. The injector head injects the contrast medium and the physiological saline at the calculated injection rate of the contrast medium and the calculated injection rate of the physiological saline, respectively.
