A holding device for a mounting part installed inside an aircraft fuselage includes an anchor plate configured to attach the holding device to a support rail of the aircraft fuselage and including at least one engagement section. The holding device further includes a holder module separably connected to the anchor plate and configured to fix the mounting part to the aircraft fuselage and having a hook section configured to positively engage the at least one engagement section so as to fasten the holder module to the anchor plate, and at least two clamping blocks disposed on the holder module.