Operational Calibration method of visible and IR channels of GMS-5 VISSR is as follows. In the visible channel, albedo is computed by the following equation. A={(C−b0)b1}2a−V0a, where C and V0 are digital counts from VISSR and V0 is bias voltage corresponding to 0 albedo respectively, other coefficients are determined from prelaunch test data. A principle of IR channel calibration depends upon a linear relation between incoming IR radiance and output voltage of IR channel. Taking the space as a cold source and a calibration shutter in VISSR as a high source, a calibration regression equation to convert output voltage of IR channel into temperature is determined. A little correction is necessary to compensate non-linear response characteristics of IR detector at low temperature. To cope with a malfunction of calibration shutter (not frequent occurrence) a method of calibration without a shutter information is developed. The monitoring of solar radiance for one year indicates a small degradation in visible channel detectors. The degradation among 4 detectors is not uniform.