An operating apparatus of an engine in a portable working machine improves an operability of a throttle lever while preventing a Run-on phenomenon or the like. The operating apparatus is provided with a first operating device for operating a throttle valve of the engine in a range from a fully closed state to a fully opened state, a switch for switching the engine between an operable state and a stoppable state, and a second operating device for operating the switch. The second operating device is structured so as to regulate an operation position of the first operating device at a time of operating the switch such that the engine is brought into the operable state, and to allow the first operating device to fully close the throttle valve at a time of operating the switch such that the engine is brought into the stoppable state.