The CALET Gamma-ray Burst Monitor (CGBM) is secondary scientific instrument of the Calorimetric Electron Telescope (CALET) mission on the International Space Station (ISS). The primary instrument Calorimeter (CAL) is capable of detecting gamma-ray bursts (GRBs) in the GeV-TeV range, and the CGBM was attached to complement CAL gamma-ray observations in the keV-MeV range. The CGBM consists of 2 Hard X-ray Monitors (HXMs) and one Soft Gamma-ray Monitor (SGM), utilizing different scintillators LaBr$_3$(Ce) and BGO respectively. The CGBM covers a broadband energy range of 7 keV - 20 MeV with a wide field of view (FOV). Since the launch on August 19, 2015, the CGBM has been sucessfully operated on the ISS for about 1.5 years, and detecting about 50 GRBs (roughly 20\% short GRBs among them) per year as expected from pre-launch estimation. The CALET also concluded memolandam of understanding (MOU) with LIGO/Virgo collaboration, and we are searching for hard X-ray and gamma-ray counterparts for gravitational wave (GW) sources. In this paper, we will report on CGBM in-orbit operation, performance and observations of GRBs and GW sources.