A power conversion device includes a capacitor for smoothing DC current; power semiconductor modules having power semiconductor devices stored in a module case and DC terminals, an AC terminal and signal terminals are extracted from an extracting part of the module case; a capacitor bus bar that connects the capacitor with the DC terminals; a first channel body having a first coolant channel formed to allow the power semiconductor modules to be inserted therein; a second channel body in which a second coolant channel for cooling the capacitor and the capacitor bus bar is formed; and a housing having a base on which the first and second channel bodies are arranged in parallel across a prescribed space and openings formed in areas of the base facing the prescribed space.