Conventional hybrid actuators can achieve a better force/torque bandwidth than a single principle actuator without losing back-drivability. However, hybrid actuators occupy space at least equal to the sum of the volumes of two or more actuators and multiple transmissions consisting of timing belts, gears, links, tendons, or Bowden-cables. Designs in which space and structural elements of a hybrid actuator are integrated have not been sufficiently studied. We have been proposed a compact direct-drive hybrid actuator with pneumatic-electromagnetic integrated structure. In the integrated design, hybrid components of an air cylinder and a linear motor were arranged around a single shaft, and the pneumatic and electromagnetic actuators shared the same moving parts (i.e., piston and moving part) and internal cylindrical spaces (i.e., cylinder and stator). Consequently, space required was less than the sum of the volumes of the two actuators.