A stellar speckle spectrometer with increased performance and flexibility has been newly developed. In this new spectrometer two synchronized detectors are used to observe a dispersed speckle pattern and a specklegram. A reflection grating is employed as a disperser. We obtained a stellar spectrum with the diffraction-limited spatial resolution of a telescope by referring to specklegrams that are simultaneously recorded with dispersed speckle patterns. A preliminary observational result is also shown.