An electrochemical reaction cell stack comprising: a plurality of interconnector-electrochemical reaction unit cell bodies (103, 103A) disposed in a first direction (z), each comprising an electrochemical reaction unit cell including an electrolyte layer, and a cathode and an anode which face each other in a first direction (z) with the electrolyte layer intervening therebetween, and an interconnector which has a first through hole defining a fuel gas flow channel (171, 172) and which is disposed on the anode side of the electrochemical reaction unit cell, and a sealing member (130, 240) which forms a fuel gas flow channel (171, 172) and which is disposed between the interconnector of one of two adjacent interconnector-electrochemical reaction unit cell composite bodies (103, 103A) among the plurality of interconnector-electrochemical reaction unit cell composite bodies (103, 103A) and the other interconnector-electrochemical reaction unit cell composite body (103, 103A), the electrochemical reaction cell stack being characterized in that: the interconnector, which the one interconnector-electrochemical reaction unit cell has, includes a coating (136, 137) forming a first surface of the interconnector, the first surface being located on a side of the interconnector opposite the anode; and the coating (136, 137) includes a first coating and a second coating (137, 137A) having reduction resistance higher than that of the first coating, the first coating forming a first surface region (152, 152A) which is a portion of the first surface of the interconnector and is located away from the first through hole, the second coating (137, 137A) forming a second surface region (153, 153A) which is a portion of the first surface of the interconnector, surrounds the first through hole, and is located between the first coating and the first through hole, an inner peripheral contour of the first coating is located outward of the inner peripheral contour of the sealing member (130, 240) as viewed in the first direction. a plurality of interconnector-electrochemical reaction unit cell bodies (103, 103A) disposed in a first direction (z), each comprising an electrochemical reaction unit cell including an electrolyte layer, and a cathode and an anode which face each other in a first direction (z) with the electrolyte layer intervening therebetween, and an interconnector which has a first through hole defining a fuel gas flow channel (171, 172) and which is disposed on the anode side of the electrochemical reaction unit cell, and a sealing member (130, 240) which forms a fuel gas flow channel (171, 172) and which is disposed between the interconnector of one of two adjacent interconnector-electrochemical reaction unit cell composite bodies (103, 103A) among the plurality of interconnector-electrochemical reaction unit cell composite bodies (103, 103A) and the other interconnector-electrochemical reaction unit cell composite body (103, 103A), the electrochemical reaction cell stack being characterized in that: the interconnector, which the one interconnector-electrochemical reaction unit cell has, includes a coating (136, 137) forming a first surface of the interconnector, the first surface being located on a side of the interconnector opposite the anode; and the coating (136, 137) includes a first coating and a second coating (137, 137A) having reduction resistance higher than that of the first coating, the first coating forming a first surface region (152, 152A) which is a portion of the first surface of the interconnector and is located away from the first through hole, the second coating (137, 137A) forming a second surface region (153, 153A) which is a portion of the first surface of the interconnector, surrounds the first through hole, and is located between the first coating and the first through hole, an inner peripheral contour of the first coating is located outward of the inner peripheral contour of the sealing member (130, 240) as viewed in the first direction. the interconnector, which the one interconnector-electrochemical reaction unit cell has, includes a coating (136, 137) forming a first surface of the interconnector, the first surface being located on a side of the interconnector opposite the anode; and the coating (136, 137) includes a first coating and a second coating (137, 137A) having reduction resistance higher than that of the first coating, the first coating forming a first surface region (152, 152A) which is a portion of the first surface of the interconnector and is located away from the first through hole, the second coating (137, 137A) forming a second surface region (153, 153A) which is a portion of the first surface of the interconnector, surrounds the first through hole, and is located between the first coating and the first through hole, an inner peripheral contour of the first coating is located outward of the inner peripheral contour of the sealing member (130, 240) as viewed in the first direction.