The present study which is titled “An Investigation of the Passive Defense in Switzerland”, explains the passive defense in the said country by a descriptive-analytic method. Due to its special features, Switzerland has been always exposed to many crises; consequently, it has experienced a lot of financial losses and causalities. As such, the countries that have experienced breakdowns and damages have especially taken into consideration the passive defense so as to keep their national capitals and critical resources; they have also considered a high priority for which regarding their defense strategies. Experience and evidence from past wars in the human history and the present era are the reasonable and undeniable instances which clearly prove the critical importance of the phenomenon of the passive defense. The findings indicated that a country like Switzerland is the symbol of attention to the passive defense; although it is not involved in any military and political conflict, it pays special attention to the issue of the passive defense. According to the abovementioned points, the present study investigates the historical background, definitions, objectives, principles and necessities, and finally, the passive defense in Switzerland.