The invention relates to a leaf module (102) for a multi-leaf collimator (132), comprising a leaf unit (104) and a leaf drive unit (106), wherein the leaf unit (104) comprises a leaf (108) for shielding beams from a selected area, and the leaf unit (104) is mounted displaceably in an adjusting direction (110), wherein the leaf drive unit (106) is designed to displace the leaf unit (104) linearly in the adjusting direction (110), and wherein the leaf drive unit (106) comprises at least one drive mechanism (112), being designed in such a way that the drive mechanism (112) operates based on pneumatic actuation. Furthermore, the invention relates to a multi-leaf collimator (132) comprising a plurality of leaf modules (102) according to the invention. The invention is based on the objective of designing a leaf module (102) and a multi-leaf collimator (132) as compactly as possible, while achieving a simple, reliable and variable adjustability of the leaf unit (104). The invention is regarded to be particularly suitable for implementation in Cobalt-60 or mid- to low-end linac radiotherapy apparatuses.