Compressor housing and exhaust gas turbine supercharger

A compressor housing for enclosing an impeller, the compressor housing comprising an inlet portion for introducing air toward the impeller and a port portion arranged adjacent to the inlet portion, a valve body for selectively opening and closing a bypass passage that bypasses the impeller in which the valve body can be rested against the port portion, wherein

• one of a side wall of the inlet portion and a side wall of the port portion has a connection hole to which a return passage for returning blow-by gas of an internal combustion engine is connected,
• a communication hole configuring a part of the return passage is formed in each of the side wall of the inlet portion and the side wall of the port portion, and
• the communication hole is formed such that a projection plane defined by projecting the communication hole onto a wall surface having the connection hole along the axis of the communication hole is contained in the connection hole.