A portable infusion device adapted to hold an infusion bag is provided. The infusion bag includes a bag body and an infusion tube connected to the bag. The portable infusion device includes a case, a plate and an elevating mechanism. The case includes an accommodating space for accommodating the bag body. The case has an aperture. The infusion tube is adapted to pass through the aperture. The plate is disposed in the receiving space and is adapted to carry the bag body. The elevating mechanism is disposed in the accommodating space and is movably connected to the case. The plate is fixed on the elevating mechanism. The elevating mechanism is adapted to push the plate to move. The portable infusion device is easily carried in use.