Electrical resistivity and Hall-effect in InSe under high pressure are accurately measured in situ. The measurement results of electrical resistivity and the temperature dependence of electrical resistivity show that InSe undergoes semiconductor-to-metal transition at 5-6 GPa and transforms from rhombohedral layered phase P1 (InSe-I) to metallic rocksalt cubic phase P3 (InSe-III) at 12 GPa. Certainly, the pressure-induced metallization of InSe results from the pressure-induced structural phase transition. In addition, Hall-effect measurements display the carrier transport behavior of InSe under pressure, which indicates that InSe undergoes a carrier-type inversion around 6.6 GPa and the increases of the carrier concentration is the dominant factor producing the decrease of the resistivity after 9.9 GPa.