An injector includes an encapsulating portion configured to encapsulate a substance intended for injection, a first application portion configured to combust ignition charge and discharge a combustion product thereby applying a primary ejection energy to the substance intended for injection that is encapsulated in the encapsulating portion, an energy accumulation portion configured to accumulate an energy to be further applied to the substance intended for injection, the energy being different from the primary ejection energy applied by the first application portion. The injector also includes a second application portion configured to release the energy accumulated in the energy accumulation portion by using the discharged combustion product thereby applying, as a secondary ejection energy, the released energy to the substance intended for injection. With this configuration, the substance intended for injection can be caused to suitably reach the target region without affecting the substance intended for injection to be ejected.