Herein disclosed is a continuously variable traction roller transmission of a double cavity type. The transmission comprises a casing; a partition wall installed in the casing to define front and rear cavities in the same; a first shaft extending through the front and rear cavities; first and second motion transmitting traction mechanisms respectively installed in the front and rear cavities, each mechanism being disposed about the first shaft and operatively connected to the same; first and second control valve body structures respectively installed in the front and rear cavities, each structure producing a hydraulic pressure for controlling the corresponding motion transmitting traction mechanism; a second shaft extending through only the rear cavity; and a mechanism for operatively connecting the second shaft to both of the first and second motion transmitting traction mechanisms. The second control valve body structure has a passage through which the second shaft is passed.