A processing apparatus having a programmable circuit including a plurality of ALUs, comprises a holding unit which holds configuration information for switching the programmable circuit from a first circuit setting to a second circuit setting, and timing information; and an updating unit which updates each ALU so as to switch the programmable circuit from the first circuit setting to the second circuit setting, wherein in switching from the first circuit setting to the second circuit setting after the programmable circuit has executed the first data processing, the updating unit, using the timing information, updates the first ALU at a timing at which last data of the first data processing is output from the first ALU, and updates the second ALU at a timing at which the last data is output from the second ALU.