A processing apparatus including a processing unit configured to process an object includes a conveying unit configured to convey an object between a transfer portion provided between an external apparatus and the processing unit, and the processing unit, a controller configured to output a request signal requesting the external apparatus to convey the object to the transfer portion, and an output unit configured to output a signal indicating a start of maintenance of the processing apparatus. The controller is configured to output to the external apparatus a signal for stopping the conveyance of the object to the transfer portion, based on the signal indicating the start of maintenance output from the output unit, after outputting the request signal.