Needleless injector

A needleless injector comprising:

• a housing part including an accommodating space that is configured to accommodate a substance intended for injection;
• an actuator configured to generate an ejection energy;
• and a plunger coupled to the housing part so as to define the accommodating space, the plunger including a base end that receives the ejection energy generated by the actuator as a driving force, a distal end that defines the accommodating space, a weakened part provided between the base end and the distal end, and, prior to activation of the actuator, a center axis of the plunger is parallel with a longitudinal axis of the housing,
• wherein upon activation of the actuator, the plunger is configured to move in the housing part by the driving force so that the distal end reaches to a deepest part of the housing part when the driving force is equal to or smaller than a predefined force, and the plunger is configured to bend by bending the center axis of the plunger at the weakened part by the driving force before the distal end reaches the deepest part of the housing part when the driving force exceeds the predefined force.