An electronic pen comprises a writing means (7) which extends into the interior of the pen, a guiding element (9) for the writing means (7), a sensor (15a) for recording images and an image processor (30) for calculating positions of the pen based on said images. The sensor (15a) is part of an imaging detector unit (15). The guiding element (9) and the detector unit (15) are arranged in a common mounting part (5) which is fixedly mounted in the interior of the pen. In such a pen, it is possible to minimize the tolerance chain between the components that convert a pen stroke on a base into a sequence of positions. This enables serial production of the pen with a small number of rejects.