The present invention relates to a medicament delivery device comprising a housing (10)； a medicament container holder (18) arranged movable in a longitudinal direction in relation to the housing, which medicament container holder (18) is arranged to accommodate a medicament container (28), which medicament container (28) is arranged as a multi-chamber container comprising medicament and diluent in different chambers； a plunger rod (70) operably arranged to act on the medicament container； retaining element (74) capable of releasably retaining said plunger rod to said housing； actuation force elements (60) capable of, upon activation, move said medicament container holder (18) in relation to said housing (10) such that said plunger rod (70) acts on said medicament container (28) for mixing said medicament and said diluent.
