The present invention relates to a dry powder inhaler used for administering a dry powder medicament carried by an elongate peelable blister strip via inhalation route. The dry powder inhaler comprises : a mouthpiece (5) through which the dry powder medicament is inhaled by the patient, a mouthpiece cover (1) for covering said mouthpiece an elongate peelable blister strip (20) containing the dry power medicament a dispensing mechanism which is actuated by the movement of the mouthpiece cover to open one blister (20a) of the blister strip and making it ready for inhaling the dry powder medicament from said opened blister a stopper (2) for preventing the reversible rotation and thus providing a correct positioning of the opened blister wherein before the inhalation of dry powder medicament, only a single movement is applied which is the mouvement of the mouthpiece cover from one position in which the mouthpiece is completely covered to another position in which the mouthpiece is completely uncovered said stopper engages to a component of said dry powder inhaler for preventing the reversible rotation of the peelable blister strip.
