A high-voltage generating device comprising: an outer case; an anvil member, a piezoelectric element and a support member which are assembled together and held and fixed in the outer case by means of an adhesive; and an inner case slidably received in the outer case and accommodating therein, a striking mechanism including a striker and a striker spring. The improvement comprises that the element mounting space in the outer case has a volume which is at least 2.5 times as large as the volume of the piezoelectric element; and the adhesive filling the element mounting space is made of a plastic having a high bonding force and a high hardness. The piezoelectric element together with the anvil member and the support member are rigidly fixed in the outer case by the adhesive, so that the vibration of the piezoelectric element impacted by the striker is accompanied by resonance vibration of the adhesive and the outer case, the resonance vibration enhancing the vibration of the piezoelectric element and prolonging the period of duration of the vibration. In consequence, a high level of high-voltage energy and, hence, a high ignition energy are obtained such as to permit the manual effort for causing the impact to be reduced.