A turning device which is capable of being coupled between a turbine and a compressor, the turning device comprising: a casing; a driving motor which is attached to be positioned higher than the casing; a driving wheel which is disposed above the casing, the driving wheel being supported on one side with respect to a reference plane that includes a driving shaft of the driving motor and is parallel to a vertical direction and, to be rotatable around a reference line that intersects the reference plane, and is rotated by the driving motor; a driven wheel which is disposed in the casing, the driven wheel being supported to be rotatable around an axis that is parallel to the reference line, and being connected to the driving wheel via a chain; a first toothed wheel which is coaxially connected to the driven wheel and has first spur teeth; a second toothed wheel having second spur teeth that engage with each of a wheel gear that is provided coaxially with a rotary shaft which extends parallel to the reference line, and the first spur teeth of the first toothed wheel; an arm member which rotatably supports the second toothed wheel; a moving mechanism which moves the second toothed wheel between an engagement position where the second toothed wheel engages with the wheel gear and a retreat position where the second toothed wheel does not engage with the wheel gear, by moving the arm member; and a cover which is attachable to and detachable from the casing and covers the driving wheel, characterized in that the turning device further comprising a coupling guard attached to a connection portion of the rotary shaft and the compressor, wherein gears which transmit a driving force from the driven wheel to the wheel gear have a two-stage configuration, wherein the driving wheel is disposed on the turbine on one side with respect to the reference plane, and the coupling guard is disposed on the compressor on the other side with respect to the reference plane. a casing; a driving motor which is attached to be positioned higher than the casing; a driving wheel which is disposed above the casing, the driving wheel being supported on one side with respect to a reference plane that includes a driving shaft of the driving motor and is parallel to a vertical direction and, to be rotatable around a reference line that intersects the reference plane, and is rotated by the driving motor; a driven wheel which is disposed in the casing, the driven wheel being supported to be rotatable around an axis that is parallel to the reference line, and being connected to the driving wheel via a chain; a first toothed wheel which is coaxially connected to the driven wheel and has first spur teeth; a second toothed wheel having second spur teeth that engage with each of a wheel gear that is provided coaxially with a rotary shaft which extends parallel to the reference line, and the first spur teeth of the first toothed wheel; an arm member which rotatably supports the second toothed wheel; a moving mechanism which moves the second toothed wheel between an engagement position where the second toothed wheel engages with the wheel gear and a retreat position where the second toothed wheel does not engage with the wheel gear, by moving the arm member; and a cover which is attachable to and detachable from the casing and covers the driving wheel, characterized in that the turning device further comprising a coupling guard attached to a connection portion of the rotary shaft and the compressor, wherein gears which transmit a driving force from the driven wheel to the wheel gear have a two-stage configuration, wherein the driving wheel is disposed on the turbine on one side with respect to the reference plane, and the coupling guard is disposed on the compressor on the other side with respect to the reference plane.