A heat exchanger includes a case, a bottom member and a plurality of heat transfer pipes (a pipe group) loaded in the heat exchanger case, in which blood flows from one end through the bottom member. The bottom member has an annular wall, a bottom surface, and a blood inlet port. The bottom surface is opposed to one end of the heat transfer pipe. The bottom surface includes a groove portion and a raised bottom portion provided on each of opposing end sides of the groove portion. The raised bottom portion is inclined such that a distance between the raised bottom portion on a side where the blood inlet port is provided and one end of the heat transfer pipe is smaller than a distance between the raised bottom portion opposite to the side where the blood inlet port is provided and one end of the heat transfer pipe.
