An injection apparatus and an injection method using the same are disclosed. The present invention uses an injection apparatus comprising: an injector which includes a mounting part on which a syringe is mounted, a needle assembly having a plurality of needles, a motor and a screw for actuating a piston of the syringe forward and backward； and a main body for controlling the forward and backward actuation of the piston of the syringe and drug injection. The present invention is configured as follows: a vacuum suction pressure is formed in the needle assembly that is in contact with the skin； injection is performed so that a drug is injected through a needle after it is determined that the needle is in close contact with the skin by comparing a sensed vacuum suction pressure value with a preset vacuum suction pressure value； and if injection is completed, the needle assembly is separated from the skin. The present invention allows for an operator's level of fatigue to be reduced, a predetermined dosage of the drug to be accurately injected, and the vacuum suction pressure to be controlled so as to prevent skin bruises.
