A warm-up system for an exhaust gas apparatus for an internal combustion engine, the warm-up system comprising: the exhaust gas apparatus including a turbocharger provided with a turbine, the turbocharger being disposed on an exhaust gas passage of the internal combustion engine, a first exhaust gas control catalyst disposed on the exhaust gas passage disposed downstream of the turbine, a bypass passage which branches from the exhaust gas passage upstream of the turbine, bypasses the turbine, and merges with the exhaust gas passage disposed upstream of the first exhaust gas control catalyst, and an adjustment unit (53, 54; 56) configured to adjust a turbine inflow exhaust gas flow rate, which is a flow rate of exhaust gas flowing into the turbine, by changing a ratio between the turbine inflow exhaust gas flow rate and a flow rate of exhaust gas flowing into the bypass passage; and an electronic control unit configured to control the turbine inflow exhaust gas flow rate by using the adjustment unit (53, 54; 56), such that the turbine inflow exhaust gas flow rate reaches a post-warm-up flow rate (Rbct) which depends on operation states of the internal combustion engine, after the first exhaust gas control catalyst and the turbine are warmed, characterised in that the electronic control unit is configured to perform a first warm-up control which warms the first exhaust gas control catalyst by controlling the turbine inflow exhaust gas flow rate, by using the adjustment unit (53, 54; 56), to reach zero, when a temperature of the first exhaust gas control catalyst is lower than an activation temperature (Tcth) of the first exhaust gas control catalyst; and the electronic control unit is configured to perform a second warm-up control which warms the turbine by controlling the turbine inflow exhaust gas flow rate, by using the adjustment unit, to reach a flow rate higher than zero and lower than the post-warm-up flow rate (Rbct) when an operating state of the internal combustion engine remains constant, such that a warmed state of the first exhaust gas control catalyst is maintained after the first exhaust gas control catalyst is warmed by the first warm-up control. the exhaust gas apparatus including a turbocharger provided with a turbine, the turbocharger being disposed on an exhaust gas passage of the internal combustion engine, a first exhaust gas control catalyst disposed on the exhaust gas passage disposed downstream of the turbine, a bypass passage which branches from the exhaust gas passage upstream of the turbine, bypasses the turbine, and merges with the exhaust gas passage disposed upstream of the first exhaust gas control catalyst, and an adjustment unit (53, 54; 56) configured to adjust a turbine inflow exhaust gas flow rate, which is a flow rate of exhaust gas flowing into the turbine, by changing a ratio between the turbine inflow exhaust gas flow rate and a flow rate of exhaust gas flowing into the bypass passage; and a turbocharger provided with a turbine, the turbocharger being disposed on an exhaust gas passage of the internal combustion engine, a first exhaust gas control catalyst disposed on the exhaust gas passage disposed downstream of the turbine, a bypass passage which branches from the exhaust gas passage upstream of the turbine, bypasses the turbine, and merges with the exhaust gas passage disposed upstream of the first exhaust gas control catalyst, and an adjustment unit (53, 54; 56) configured to adjust a turbine inflow exhaust gas flow rate, which is a flow rate of exhaust gas flowing into the turbine, by changing a ratio between the turbine inflow exhaust gas flow rate and a flow rate of exhaust gas flowing into the bypass passage; and an electronic control unit configured to control the turbine inflow exhaust gas flow rate by using the adjustment unit (53, 54; 56), such that the turbine inflow exhaust gas flow rate reaches a post-warm-up flow rate (Rbct) which depends on operation states of the internal combustion engine, after the first exhaust gas control catalyst and the turbine are warmed, characterised in that the electronic control unit is configured to perform a first warm-up control which warms the first exhaust gas control catalyst by controlling the turbine inflow exhaust gas flow rate, by using the adjustment unit (53, 54; 56), to reach zero, when a temperature of the first exhaust gas control catalyst is lower than an activation temperature (Tcth) of the first exhaust gas control catalyst; and the electronic control unit is configured to perform a second warm-up control which warms the turbine by controlling the turbine inflow exhaust gas flow rate, by using the adjustment unit, to reach a flow rate higher than zero and lower than the post-warm-up flow rate (Rbct) when an operating state of the internal combustion engine remains constant, such that a warmed state of the first exhaust gas control catalyst is maintained after the first exhaust gas control catalyst is warmed by the first warm-up control.