Power semiconductor device and power conversion device

A power semiconductor device comprising:

• a power module unit;
• an adhesive sheet bonded to the power module unit;
• a support member connected to the power module unit with the adhesive sheet interposed between the power module unit and the support member;
• and
• a flow prevention frame sandwiched between the power module unit and the support member and placed around the adhesive sheet, wherein
• the flow prevention frame is made of a porous body,
• the adhesive sheet has an outer peripheral surface adjoining an inner peripheral surface of the flow prevention frame, and
• a value obtained by dividing a maximum value of an internal pressure on the outer peripheral surface by a minimum value of the internal pressure is more than or equal to 1 and less than or equal to 10.