PURPOSE: To attain a data compressing method for compressing data by adding and storing the data and a data checking method for comparing the compressed data with reference data.

CONSTITUTION: An added result of reference data in each row out of reference data successively allocated to respective nodes of a virtual XY matrix and an added result of the reference data in each column are previously stored in a reference data storing means 1, successively inputted input data are successively allocated to respective nodes of the matrix, the added result of each row is stored in a 1st storing means 2, the added result of each column is stored in a 2nd storing means 3, and the added result of the reference data are compared with the added result of the input data by a judging means 8 to check the data.