A microlithographic projection exposure mirror has a mirror substrate (12, 32), a reflection layer system (21, 41) for reflecting electromagnetic radiation that is incident on the mirror's optical effective surface, and at least one piezoelectric layer (16, 36), which is arranged between the mirror substrate and the reflection layer system and to which an electric field for producing a locally variable deformation is applied by a first electrode arrangement situated on the side of the piezoelectric layer facing the reflection layer system, and by a second electrode arrangement situated on the side of the piezoelectric layer facing the mirror substrate. One of the electrode arrangements is assigned a mediator layer (17, 37, 51, 52, 53, 71) for setting an at least regionally continuous profile of the electrical potential along the respective electrode arrangement. The mediator layer has at least two mutually electrically insulated regions (17a, 17b, 17c, . . . ; 37a, 37b, 37c, . . . ).