The injection device comprises a medicine container, means for injecting medicine from the medicine container to a patient through a needle, a skin contact surface crossable by the needle and having protrusions which are pressed around the injection site when the injection device is applied on the patient's skin for the injection, the protrusions being arranged so as to reduce the pain caused by the penetration of the needle, and a sensor for detecting contact of the patient's skin with the skin contact surface, wherein a predetermined force of application of the injection device on the patient's skin is required for the sensor to detect the patient's skin. According to another aspect of the invention, the protrusions include first and second protrusions, wherein the first protrusions come into contact with the patient's skin as the device is applied with a first force and the second protrusions come into contact with the patient's skin as the device is applied with a second force, the second force being greater than the first force.
