Heat exchanger, heat exchanger unit, and refrigeration cycle apparatus

A heat exchanger comprising:

• a heat exchange element extending in a first direction;
• and
• a header to which the heat exchange element is connected,
• the heat exchange element including
• at least one heat transfer tube extending in the first direction, and
• a fin provided on part of an edge portion of the at least one heat transfer tube in a second direction crossing orthogonally with the first direction,
• wherein an end portion in the first direction of the heat exchange element includes
• an insertion part being inserted into an interior of the header,
• an abutment part abutting the header in a part other than the insertion part, and
• a spaced-apart part being spaced apart from the header in a part other than the insertion part, and
• wherein the abutment part is located between the insertion part and the spaced-apart part, and at least one part of the abutment part is a part of an end face in the first direction of the fin.