Radiowave environment data correction that uses the data measurement results obtained at measuring points in a base station peripheral area provided for a wireless communications system, is achieved accurately at a limited number of measuring points. A radiowave environment data correcting system includes correction data determining means that determines correction data for sub-areas, the sub-areas being regions into which an assessment area is divided, on the basis of data measurement results obtained at measuring points belonging to the sub-areas, wherein division into the area is based on an area usage division that is a division predefined according to a particular layout of objects or spaces in the assessment area. The system may also include sub-area dividing means that divides the assessment area into sub-areas in accordance with the area usage division, correction data calculating means that calculates the correction data in the sub-areas using the data measurement results obtained at the measuring points existing in the sub-areas, and radiowave environment data correcting means that uses the calculated correction data to correct radiowave environment data present inside the sub-areas.