A device for injecting a medicament is provided. The device has a housing with a container within it which can hold a medicament. At its proximal end the container has a needle and a stopper. The device includes a plunger which at one end can engage the stopper. At the opposite end, the plunger can engage a first resilient member to move the stopper within the container to inject the medicament from the container. The device includes a collar with distal and proximal ends, the distal end engaging with a carriage and causing its rotation and the proximal end engaging with a second resilient member. The second resilient member can engage with a skin sensor which has distal and proximal ends. At the proximal end, the skin sensor can contact an injection site. The housing has a cap which can reduce or prevent movement of the skin sensor.