To provide the mounting structure of a valve actuator, which can be made compact as a whole with a simple configuration and enables operation of a valve by commonly using it by an automatic actuator or manual actuator, which enables direct mounting upon mounting of the automatic actuator and improves mounting work efficiency of the valve and the actuator, and which enables an operation while preventing fingers from being pinched, and with which opening and closing of the valve can be accurately controlled.

In the mounting structure of the valve actuator, a mounting cover body 1 is mounted and fixed on the upper face of an axial support part 9 where the stem 8 of a valve body 7 is installed. The mounting cover body 1 includes a substrate 11 having a mounting opening 10, and a hanging side plate 12. The mounting cover body 1 is positioned and fixed to the valve body 7 by screwing a valve fixing bolt 2 from the hanging side plate 12 to an outer circumference face in the upper part of the axial support part 9. An actuator 5 for an automatic operation or a manual actuator 6 for a manual operation can be mounted on the mounting cover body 1.