Through the analysis of calibration data of Multi Spectral Scanner onboard Landsat, the followings characteristics in the responsivity of the detectors are found. (1) Both long and short term variations are found. (2) Silicon photodiode detectors for the spectral band of Band 7 (0.8-1.1μm) are more stable than photomultiplier tubes used for Bands 4, 5 and 6 (0.5-0.6, 0.6-0.7 and 0.7-0.8μm).(3)The hysterisis is found in photomultiplier tube with a larger gain just after the observation of bright scene. (4) It seems a positive correlation exists between ambient temperature and photomultiplier tube detector output.