This paper presents an efficient map generation technique for evaluating the intensity of electromagnetic (EM) radiation associated with information leakage for cryptographic devices at the PCB level. First, we investigate the relation between the intensity of the overall EM radiation and the intensity of EM information leakage on a cryptographic device. For this purpose, we prepare a map of the magnetic field on the device by using an EM scanning system, after which we perform correlation electromagnetic analysis (CEMA) at all measurement points on the device, including points above the cryptographic module. The examined device is a standard evaluation board for cryptographic modules (SASEBO), where a cryptographic circuit is implemented on one of the FPGAs on the board. With this experiment, we demonstrate that an efficient map of EM radiation associated with information leakage can be generated on the basis of an EM radiation map. We also confirm that the generated map is in fair agreement with the corresponding map obtained from exhaustive CEMA.