The present invention provides a control method for an error detection & correction apparatus, comprising a plurality of data processing apparatuses which reside in a data communications path and partake in exchanging data by the unit of error correcting code, and a plurality of information exchange paths which are installed between the plurality of data processing apparatuses; and generating a true syndrome by exchanging a partial syndrome relating to a part of the data partaken by each of the data processing apparatuses by way of the information exchange paths, comprising the step of exchanging renewal information relating to a part of the data partaken by each of the data processing apparatuses with the other data processing apparatus by way of the information exchange path.