Provided is a power conversion apparatus that includes a power semiconductor module, a smoothing capacitor module, an alternating-current bus bar, a control circuit unit to control the power semiconductor element, and a flow channel formation body to form a flow channel through which a cooling medium flows. The power semiconductor module has a first heat dissipation portion and a second heat dissipation portion facing the first heat dissipation portion. A flow channel formation body external portion of the flow channel formation body has a first surface wall that faces the first heat dissipation portion with the flow channel therebetween, a second surface wall that faces the second heat dissipation portion with the flow channel therebetween, and a sidewall to connect the first surface wall and the second surface wall. The sidewall has an opening to insert the power semiconductor module into the flow channel.