The device (1) has a lancet guide to hold a lancet (10), and a lancet drive (2) for generating drive force to move the lancet guide along a piercing path in a piercing direction. A retention mechanism generates a magnetic retention force for retaining the lancet guide in a tensioned position. A trigger is actuated to reduce the retention force and allows the drive force to accelerate the lancet guide in the piercing direction. A control unit controls the reduction in retention force and regulates piercing depth. The lancet drive comprises an armature plate positioned on the lancet guide. An independent claim is also included for a method for operating a lancet device.