A system, comprising: an electric rotary machine including a stator coil, an estimator configured to estimate a temperature of the stator coil of the electric rotary machine, and cooling oil configured to cool the electric rotary machine, characterized in that the estimator comprises: an electronic control unit configured to calculate two state quantities being an estimated maximum coil temperature (Tm) and an estimated value of a correction signal indicating a temperature (Tr) by using at least one input signal (I, ω, To, Ta, fc) and a relational expression that represents a thermal resistance model; and a correction sensor embodied as a temperature sensor configured to measure a temperature (Tra) indicating a correction signal for correcting the two state quantities (Tm, Tr), the electronic control unit being configured to output a value for correcting the two state quantities (Tm, Tr) based on the correction signal, and change the relational expression that represents the thermal resistance model in accordance with an oil flow related value that relates to a change of flow of the cooling oil, the correction sensor being arranged such that the correction sensor is in contact with a metal member that includes a coil conductive wire that constitutes the stator coil, a terminal connected to the coil conductive wire, and a power line connected between the coil conductive wire and the terminal, at a point not being in contact with the cooling oil. an electric rotary machine including a stator coil, an estimator configured to estimate a temperature of the stator coil of the electric rotary machine, and cooling oil configured to cool the electric rotary machine, characterized in that the estimator comprises: an electronic control unit configured to calculate two state quantities being an estimated maximum coil temperature (Tm) and an estimated value of a correction signal indicating a temperature (Tr) by using at least one input signal (I, ω, To, Ta, fc) and a relational expression that represents a thermal resistance model; and a correction sensor embodied as a temperature sensor configured to measure a temperature (Tra) indicating a correction signal for correcting the two state quantities (Tm, Tr), the electronic control unit being configured to output a value for correcting the two state quantities (Tm, Tr) based on the correction signal, and change the relational expression that represents the thermal resistance model in accordance with an oil flow related value that relates to a change of flow of the cooling oil, the correction sensor being arranged such that the correction sensor is in contact with a metal member that includes a coil conductive wire that constitutes the stator coil, a terminal connected to the coil conductive wire, and a power line connected between the coil conductive wire and the terminal, at a point not being in contact with the cooling oil. an electronic control unit configured to calculate two state quantities being an estimated maximum coil temperature (Tm) and an estimated value of a correction signal indicating a temperature (Tr) by using at least one input signal (I, ω, To, Ta, fc) and a relational expression that represents a thermal resistance model; and a correction sensor embodied as a temperature sensor configured to measure a temperature (Tra) indicating a correction signal for correcting the two state quantities (Tm, Tr), the electronic control unit being configured to output a value for correcting the two state quantities (Tm, Tr) based on the correction signal, and change the relational expression that represents the thermal resistance model in accordance with an oil flow related value that relates to a change of flow of the cooling oil, output a value for correcting the two state quantities (Tm, Tr) based on the correction signal, and change the relational expression that represents the thermal resistance model in accordance with an oil flow related value that relates to a change of flow of the cooling oil, the correction sensor being arranged such that the correction sensor is in contact with a metal member that includes a coil conductive wire that constitutes the stator coil, a terminal connected to the coil conductive wire, and a power line connected between the coil conductive wire and the terminal, at a point not being in contact with the cooling oil.