A sheet processing apparatus for processing sheets each with a wireless tag includes a roller, a wireless tag reader/writer, and a controller configured to control the roller to convey a first sheet with a first tag along a path, control the reader/writer to acquire first strengths of radio signals received from the first tag during the conveyance and second strengths of radio signals received from wireless tags of sheets not being conveyed, determine a threshold value of signal strength for distinguishing a wireless tag being conveyed from wireless tags not being conveyed based on the first and second strengths, and control the roller to convey a second sheet with a second tag and control the reader/writer to write to the second tag when a strength of a radio signal from the second tag is greater than or equal to the threshold value.

A sheet processing apparatus for processing sheets each with a wireless tag includes a roller, a wireless tag reader/writer, and a controller configured to control the roller to convey a first sheet with a first tag along a path, control the reader/writer to acquire first strengths of radio signals received from the first tag during the conveyance and second strengths of radio signals received from wireless tags of sheets not being conveyed, determine a threshold value of signal strength for distinguishing a wireless tag being conveyed from wireless tags not being conveyed based on the first and second strengths, and control the roller to convey a second sheet with a second tag and control the reader/writer to write to the second tag when a strength of a radio signal from the second tag is greater than or equal to the threshold value.