I talk about the newly developed near-infrared (0.9-2.5um) imager and spectrograph ISLE for the Cassegrain focus (f/18) of the 1.88 m telescope at Okayama Astrophysical Observatory (OAO). The detector of ISLE is a HAWAII 1024 x 1024 HgCdTe array. The field of view and the pixel scale are 4.2 x 4.2 arcmin^2 and 0.25 arcsec / pixel, respectively. The pixel scale is optimized to sample the light profile of a point source under typical near-infrared seeing condition of OAO (around 1 arcsec). The spectroscopy mode of ISLE provides a capability of long-slit spectroscopy with a spectral resolution R ranging from 500 to 4800. We developed a low-noise readout electronics for the detector and achieved a readout noise lower than 10 e with single sampling readout. Applying a special readout technique, we also succeeded to suppress so-called \"reset anomaly\" of the detector significantly.<br />