A drug infusion pump is provided. The drug infusion pump includes a main body including a drive motor and a processor, and a cartridge module including a pump module and a drug cartridge and detachably provided in the main body. When the cartridge module is fitted in the main body, the pump module and the drug cartridge are accommodated in the main body and the pump module is coupled to the drive motor. The drug infusion pump is configured such that the pump module is coupled with the drive motor when the cartridge module is fitted in the main body. Accordingly, the cartridge may be easily separated and replaced so as to address a problem of a patients inconvenience in using the drug infusion pump.