A power inverter, comprising: a chassis that comprises an upper opening (400, 402) at an upper end and a lower opening at a lower end of the chassis; a power module that is housed in the chassis and comprises a plurality of switching devices (328, 330) for an upper arm and a lower arm that make up an inverter circuit, a metal board that releases heat generated by the plurality of the switching devices (328, 330), and a DC terminal and an AC terminal; a smoothing capacitor module that comprises a DC terminal (502, 504) and smoothes a DC voltage applied to the DC terminal (502, 504) of the smoothing capacitor module, with the DC terminal (502, 504) of the smoothing capacitor module electrically connected with the DC terminal of the power module; a gate drive circuit, housed in the chassis, that drives the power module; wherein: the power module is provided in a first region; a semiconductor module for auxiliaries and the smoothing capacitor module are provided in a second region; characterised in that the power inverter further comprises a space that links the first region and the second region is created between a side of a coolant passage and the chassis, and the DC terminal (502, 504) of the smoothing capacitor module and the DC terminal of the power module are electrically connected with each other through the space, an upper cover and a lower cover that cover the upper opening (400, 402) and the lower opening respectively; wherein: the coolant passage, on which the power module is mounted, is provided substantially parallel to the upper cover or the lower cover in the chassis; wherein; the chassis is provided with the first region between the upper cover and the coolant passage and the second region between the lower cover and the coolant passage, by providing the coolant passage inside the chassis. a chassis that comprises an upper opening (400, 402) at an upper end and a lower opening at a lower end of the chassis; a power module that is housed in the chassis and comprises a plurality of switching devices (328, 330) for an upper arm and a lower arm that make up an inverter circuit, a metal board that releases heat generated by the plurality of the switching devices (328, 330), and a DC terminal and an AC terminal; a smoothing capacitor module that comprises a DC terminal (502, 504) and smoothes a DC voltage applied to the DC terminal (502, 504) of the smoothing capacitor module, with the DC terminal (502, 504) of the smoothing capacitor module electrically connected with the DC terminal of the power module; a gate drive circuit, housed in the chassis, that drives the power module; wherein: the power module is provided in a first region; a semiconductor module for auxiliaries and the smoothing capacitor module are provided in a second region; the power module is provided in a first region; a semiconductor module for auxiliaries and the smoothing capacitor module are provided in a second region; characterised in that the power inverter further comprises a space that links the first region and the second region is created between a side of a coolant passage and the chassis, and the DC terminal (502, 504) of the smoothing capacitor module and the DC terminal of the power module are electrically connected with each other through the space, an upper cover and a lower cover that cover the upper opening (400, 402) and the lower opening respectively; wherein: the coolant passage, on which the power module is mounted, is provided substantially parallel to the upper cover or the lower cover in the chassis; wherein; the chassis is provided with the first region between the upper cover and the coolant passage and the second region between the lower cover and the coolant passage, by providing the coolant passage inside the chassis. the coolant passage, on which the power module is mounted, is provided substantially parallel to the upper cover or the lower cover in the chassis; wherein; the chassis is provided with the first region between the upper cover and the coolant passage and the second region between the lower cover and the coolant passage, by providing the coolant passage inside the chassis.