There is described a medication delivery device comprising a housing, a door (88) which, in its open position, permits insertion/removal of a medication container (83) into/from said housing, a door opening mechanism (89, 123, 125, 126, 82) for opening/closing said door (88), and a push member which can be moved axially from a retracted position, located outside said medication container (83), to enter said medication container (83) and push liquid medication contained in said medication container (83) out of said medication container (83) to deliver it to a patient, and then returned to its retracted position, characterized by comprising a lock mechanism (94, 129) for locking at least part of said door opening mechanism (89, 123, 125, 126, 82), to prevent opening of said door (88), when said push member is inside said medication container (83) and for unlocking said door opening mechanism (89, 123, 125, 126, 82) when said push member is in its retracted position.
