A control valve pneumatic actuator using a transparent casing includes a casing having a cylindrical shape and made of a transparent material to enable an inside of the casing to be observed from outside, a driveshaft penetrating the inside of the casing, a diaphragm fixedly connected to the driveshaft inside the casing and vertically moving in the casing according to a movement of the driveshaft, a ring holder attached to an outer circumferential of the diaphragm and having a groove having a C-shape, a rubber ring inserted into the groove of the ring holder, a control valve connected to a lower portion of the drive shaft extending below the casing, and a yoke arranged below the casing and connecting the casing to the control valve.