Abstract: A connection unit for air feeding tube is a connection unit to which an air feeding tube is connectable and fixable and which includes: a first pipe having an opening through which gas from the air feeding tube flows in; a second pipe that is configured to be arrangeable substantially parallel to a surface of a bed used in an examination, and includes an opening through which the gas flows out; and an air feeding flow path which is formed to include the two openings and through which the gas is fed. When the air feeding tube is fixed to the connection unit for air feeding tube and is used, a part of the air feeding flow path for the gas is formed so as to pass through an area located at a position opposite to a gravitational direction with respect to a central axis of the second pipe.