The Improved Limb Atmospheric Spectrometer-II (ILAS-II) onboard the Advanced Earth Observing Satellite-II (ADEOS-II) was successfully launched on 14 December, 2002 from National Space Development Agency of Japan (NASDA)’s Tanegashima Space Center. ILAS-II is a solar-occupation atmospheric sensor which will measure vertical profiles of O3, HNO3, NO2, N2O, CH4, H2O, ClONO2, aerosol extinction coefficients, etc. with four grating spectrometers. After the checkout period of the ILAS-II which is scheduled in January-February, 2003, ILAS-II will make routine measurements from early April. An initial checkout (ICO) operation was done on 20-23 January, 2003. Data taken during the ICO period suggest that ILAS-II was functioning normally as designed. Signal-to-noise ratio (SNR) for each channel showed good quality of the ILAS-II data except for Ch.3. Preliminary comparison of ILAS-II O3 profiles with ozonesondes showed good agreements. A validation campaign is scheduled to be taken place in Kiruna, Sweden in 2003, when several balloon-borne measurements are planned.