An electric heater comprising: a heater section (A1-A4) having a heater element which generates heat by being supplied with electric power; a fin which transfers heat of the heater section to outside air; a housing which holds the heater section and the fin stacked to one another in a vertical direction intersecting with a flow direction of the outside air; and a spring member assembled to the housing to apply a compression force to the heater section (A1-A4) and the fin in a stacking direction thereof, wherein the heater section (A1-A4) includes: an upper conductive member and a lower conductive member which are arranged to sandwich the heater element from both sides in the stacking direction and touch the heater element to supply electric power to the heater element from outside; and a holder which holds the heater element, the upper conductive member, and the lower conductive member, wherein the holder is provided with upstream and downstream upper engagement portions (21b, 20b) which engage with the upper conductive member from a side opposite to the heater element with respect to the upper conductive member, and upstream and downstream lower engagement portions (21c, 20c) which engage with the lower conductive member from a side opposite to the heater element with respect to the lower conductive member, a vertical distance between the upstream upper engagement portion and the upstream lower engagement portion and a vertical distance between the downstream upper engagement portion and the downstream lower engagement portion are set to be longer than a total vertical dimension of a thickness of the upper conductive member, a thickness of the lower conductive member, and a thickness of the heater element, wherein the holder is configured to allow the upper conductive member to be displaced in the vertical direction closer to and away from the lower conductive member in a gap between the upstream upper engagement portion and the upstream lower engagement portion and in a gap between the downstream upper engagement portion and the downstream lower engagement portion. a heater section (A1-A4) having a heater element which generates heat by being supplied with electric power; a fin which transfers heat of the heater section to outside air; a housing which holds the heater section and the fin stacked to one another in a vertical direction intersecting with a flow direction of the outside air; and a spring member assembled to the housing to apply a compression force to the heater section (A1-A4) and the fin in a stacking direction thereof, wherein the heater section (A1-A4) includes: an upper conductive member and a lower conductive member which are arranged to sandwich the heater element from both sides in the stacking direction and touch the heater element to supply electric power to the heater element from outside; and a holder which holds the heater element, the upper conductive member, and the lower conductive member, wherein the holder is provided with upstream and downstream upper engagement portions (21b, 20b) which engage with the upper conductive member from a side opposite to the heater element with respect to the upper conductive member, and upstream and downstream lower engagement portions (21c, 20c) which engage with the lower conductive member from a side opposite to the heater element with respect to the lower conductive member, a vertical distance between the upstream upper engagement portion and the upstream lower engagement portion and a vertical distance between the downstream upper engagement portion and the downstream lower engagement portion are set to be longer than a total vertical dimension of a thickness of the upper conductive member, a thickness of the lower conductive member, and a thickness of the heater element, wherein the holder is configured to allow the upper conductive member to be displaced in the vertical direction closer to and away from the lower conductive member in a gap between the upstream upper engagement portion and the upstream lower engagement portion and in a gap between the downstream upper engagement portion and the downstream lower engagement portion.