A heat exchange element sheet having a layered structure containing a porous base material and a resin layer, the heat exchange element sheet having a first face and a second face, an outermost layer at the first face of the heat exchange element sheet being a resin layer, the resin layer containing polyvinyl pyrrolidone and/or a vinyl pyrrolidone copolymer, the resin layer containing a fungicide, wherein the fungicide is a solid material in the form of particles, the heat exchange element sheet being characterised in that the fungicide particles have diameters of 10 nm or more and 10,000 nm or less, and wherein a ratio between the diameter of the fungicide and a thickness of the resin layer (diameter of fungicide / thickness of resin layer) is 0.5 to 10, wherein the diameter of the fungicide particles is determined from an image taken of a first face or cross section of the heat exchange element sheet observed by SEM, an area of each solid fungicide particle found in the image is measured by an image analysis technique, and a diameter of a perfect circle having the same area as the measured one is calculated, and an average is calculated to represent the diameter of the solid fungicide particles, and the thickness of the resin layer is determined from a SEM cross section image or a TEM cross section image of the heat exchange element sheet, the thickness of the resin layer being considered to be represented by a distance from a first surface of the heat exchange element sheet having penetrated into the porous base material to an interface between the resin layer and the porous base material, and resin layer components existing in pores of the porous base material are ignored in determining the thickness of the resin layer. the heat exchange element sheet having a first face and a second face, an outermost layer at the first face of the heat exchange element sheet being a resin layer, the resin layer containing polyvinyl pyrrolidone and/or a vinyl pyrrolidone copolymer, the resin layer containing a fungicide, wherein the fungicide is a solid material in the form of particles, the heat exchange element sheet being characterised in that the fungicide particles have diameters of 10 nm or more and 10,000 nm or less, and wherein a ratio between the diameter of the fungicide and a thickness of the resin layer (diameter of fungicide / thickness of resin layer) is 0.5 to 10, wherein the diameter of the fungicide particles is determined from an image taken of a first face or cross section of the heat exchange element sheet observed by SEM, an area of each solid fungicide particle found in the image is measured by an image analysis technique, and a diameter of a perfect circle having the same area as the measured one is calculated, and an average is calculated to represent the diameter of the solid fungicide particles, and the thickness of the resin layer is determined from a SEM cross section image or a TEM cross section image of the heat exchange element sheet, the thickness of the resin layer being considered to be represented by a distance from a first surface of the heat exchange element sheet having penetrated into the porous base material to an interface between the resin layer and the porous base material, and resin layer components existing in pores of the porous base material are ignored in determining the thickness of the resin layer. the diameter of the fungicide particles is determined from an image taken of a first face or cross section of the heat exchange element sheet observed by SEM, an area of each solid fungicide particle found in the image is measured by an image analysis technique, and a diameter of a perfect circle having the same area as the measured one is calculated, and an average is calculated to represent the diameter of the solid fungicide particles, and the thickness of the resin layer is determined from a SEM cross section image or a TEM cross section image of the heat exchange element sheet, the thickness of the resin layer being considered to be represented by a distance from a first surface of the heat exchange element sheet having penetrated into the porous base material to an interface between the resin layer and the porous base material, and resin layer components existing in pores of the porous base material are ignored in determining the thickness of the resin layer.