A control apparatus for controlling rotation of a shaft about an axis in a front-and-rear direction, comprising: a housing including front and rear housing mounts (3, 4) which are spaced apart from each other in the front-and-rear direction; a roller interposed between said front and rear housing mounts (3, 4) and releasably and rotatably connected to said rear housing mount to be rotatable relative to said housing about the axis; an endless operating cord looped on said roller to be operated to rotate said roller about the axis; and a coupling mechanism rotatably disposed between said front housing mount and said roller, characterized in that: said coupling mechanism has a front coupling member which is disposed to be coupled with and rotate the shaft, a rear coupling member which is releasably connected to said roller by a rearward resilient force along the axis to be rotated with said roller, and which is movable along the axis and non-rotatable about the axis relative to said front coupling member so as to synchronously rotate said front coupling member when being rotated through the rotation of said roller, and a resilient member which is disposed to apply the rearward resilient force to said rear coupling member; said coupling mechanism being configured such that said roller is movable relative to said housing, upon an excess downward pulling force applied to said operating cord, from a driving position, where said roller is disposed within said housing and rotated by pulling said operating cord so as to rotate said coupling mechanism and the shaft, to a releasing position, where said rear coupling member is moved forwardly toward said front coupling member against the rearward resilient force to release connection of said roller with said rear coupling member and said rear housing mount so as to permit removal of said roller from said housing. a housing including front and rear housing mounts (3, 4) which are spaced apart from each other in the front-and-rear direction; a roller interposed between said front and rear housing mounts (3, 4) and releasably and rotatably connected to said rear housing mount to be rotatable relative to said housing about the axis; an endless operating cord looped on said roller to be operated to rotate said roller about the axis; and a coupling mechanism rotatably disposed between said front housing mount and said roller, characterized in that: said coupling mechanism has a front coupling member which is disposed to be coupled with and rotate the shaft, a rear coupling member which is releasably connected to said roller by a rearward resilient force along the axis to be rotated with said roller, and which is movable along the axis and non-rotatable about the axis relative to said front coupling member so as to synchronously rotate said front coupling member when being rotated through the rotation of said roller, and a resilient member which is disposed to apply the rearward resilient force to said rear coupling member; said coupling mechanism being configured such that said roller is movable relative to said housing, upon an excess downward pulling force applied to said operating cord, from a driving position, where said roller is disposed within said housing and rotated by pulling said operating cord so as to rotate said coupling mechanism and the shaft, to a releasing position, where said rear coupling member is moved forwardly toward said front coupling member against the rearward resilient force to release connection of said roller with said rear coupling member and said rear housing mount so as to permit removal of said roller from said housing. said coupling mechanism has a front coupling member which is disposed to be coupled with and rotate the shaft, a rear coupling member which is releasably connected to said roller by a rearward resilient force along the axis to be rotated with said roller, and which is movable along the axis and non-rotatable about the axis relative to said front coupling member so as to synchronously rotate said front coupling member when being rotated through the rotation of said roller, and a resilient member which is disposed to apply the rearward resilient force to said rear coupling member; said coupling mechanism being configured such that said roller is movable relative to said housing, upon an excess downward pulling force applied to said operating cord, from a driving position, where said roller is disposed within said housing and rotated by pulling said operating cord so as to rotate said coupling mechanism and the shaft, to a releasing position, where said rear coupling member is moved forwardly toward said front coupling member against the rearward resilient force to release connection of said roller with said rear coupling member and said rear housing mount so as to permit removal of said roller from said housing.