The utility model relates to a mask bow device of a working cap, which comprises a setting unit, a fixing unit and a two pivot setting unit.The setting unit includes two connecting pieces which are respectively arranged on the working cap and two internal positioning pieces which are respectively connected with the connecting pieces. Each internal positioning piece forms a plurality of internal tooth lines extending outwards.The fixing unit comprises a fixing bow suitable for connecting the face shield and two external locating parts which are respectively pressed against the internal locating parts, each of which forms a plurality of external tooth patterns extending inward and meshing with the internal tooth patterns.Through the meshing of the internal teeth and the external teeth, the mask can be rotated in segments, so that the user can adjust the mask in segments to an appropriate angle of inclination according to their own needs.一種工作帽之面罩弓裝置，包含一設置單元、一固定單元，及二樞設單元。該設置單元包括二適用於分別設置在該工作帽的連接件，及二分別連接該等連接件的內定位件，每一內定位件形成複數朝外延伸的內齒紋。該固定單元包括一適用於連接該護面罩的固定弓，及二分別分別壓抵該等內定位件的外定位件，每一外定位件形成複數朝內延伸並與該等內齒紋相嚙合的外齒紋。透過相互嚙合的該等內齒紋及該等外齒紋可進行有段式旋轉，讓使用者可依自身需求將該護面罩有段位地調整至適當的傾斜角度。
