The present invention relates to a medicament delivery device (10) comprising a base member (12) provided with an attachment surface (16, 100) for attachment to a skin surface of a user. The device (10) further comprises a unit (24, 96) pivotably connected to said base member (12), which unit (24, 96) comprises drive means (28, 30), a plunger rod (36) connected to said drive means, a medicament container (54) containing medicament to be pressurised by said plunger rod and said drive means, a valve arrangement (66) fluidly connectable to said medicament container, an injection needle (72) fluidly connected to said valve arrangement, and control means (86, 88) operably connected to said valve arrangement for opening and closing a fluid path between the medicament container and the injection needle, wherein a pivoting action of said unit (24, 96) in relation to said base member (12) causes a penetration of said injection needle (72).