An NMR MAS probe head (1) has an MAS stator (7) with a base bearing (8) and a front bearing (75) for receiving a substance to be measured at a measurement position within an MAS rotor. The front bearing has an opening for inserting the MAS rotor into the space between the base bearing and the front bearing. The opening can be closed by a closing device that, in a loading state, opens and, in a measuring state, closes the opening by means of a movement that is transverse with respect to an axis (a) through the centers of the base bearing and the opening of the front bearing of the MAS stator. This enables automated loading and unloading of the MAS rotor in the space between the base bearing and the front bearing inside the MAS stator in a simple way.