A method of processing a target object includes (a) exposing a resist mask to active species of hydrogen generated by exciting plasma of a hydrogen-containing gas within a processing vessel while the target object is mounted on a mounting table provided in the processing vessel; and (b) etching a hard mask layer by exciting plasma of an etchant gas within the processing vessel after the exposing of the resist mask to the active species of hydrogen. The plasma is excited by applying of a high frequency power for plasma excitation to an upper electrode. In the method, a distance between the upper electrode and the mounting table in the etching of the hard mask layer ((b) process) is set to be larger than a distance between the upper electrode and the mounting table in the exposing of the resist mask to the active species of hydrogen ((a) process).