A medical fluid injector device injecting a patient with a mixed medical fluid provided by a plurality of medical fluids and capable of simply setting injection conditions for the mixed medical fluid. A medical fluid injector (100) includes an injector head (110) injecting a diluted contrast medium into a patient and a controller unit (50). The controller unit (50) performs a process of receiving an input relating to an injection rate of the diluted medical fluid, a process of receiving an input relating to a mixture ratio by an operator, a process of calculating an injection rate of a contrast medium based on the mixture ratio, and a process of calculating an injection rate of physiological saline based on the mixture ratio. The injector head (110) 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.
