A display device comprising: a substrate; a driving layer disposed on the substrate, and comprising: first driving circuit groups (UC1, UC2) each comprising N first pixel driving circuits (CK1 to CK32) and photo pixels (HX1 to HX4), wherein N is a natural number and each of the photo pixels (HX1 to HX4) comprises a photo driving circuit (PK1 to PK4) and a photo sensor electrically connected to the photo driving circuit (PK1 to PK4); a display element layer disposed on the driving layer, and comprising first display element groups (UP1, UP2) each comprising N first display elements electrically connected to the respective N first pixel driving circuits (CK1 to CK32); and second driving circuit groups (UC3, UC4) comprising N second pixel driving circuits, wherein minimum distances between first color display elements included in the plurality of first display elements, which are measured in a first predetermined direction in a plan view, are substantially the same, wherein a distance between two first pixel driving circuits (CK4, CK9) of the N first pixel driving circuits (CK1 to CK32) adjacent to each other in a second predetermined direction with a photo pixel of the photo pixels (HX1 to HX4) therebetween in the plan view is larger than a distance between two other first pixel driving circuits (CK3, CK4) of the N first pixel driving circuits disposed in the second predetermined direction, and wherein the each display element layer further comprises N second display elements electrically connected to the N second pixel driving circuits, wherein a display area where an image is displayed and a non-display area adjacent to the display area are defined on the display device, wherein the display area comprises a normal display area and a light sensing area for sensing a user's input by an incident light, wherein the first driving circuit groups (UC1, UC2) and the first display element groups (UP1, UP2) are disposed in the light sensing area in the plan view, wherein the second driving circuit groups (UC3, UC4) and the second display element groups (UP3, UP4) are disposed in the normal display area in the plan view, characterised in that an area which each of the N first pixel driving circuits (CK1 to CK8) occupies is smaller than an area which each of the N second pixel driving circuits occupies (CK17 to CK24). a substrate; a driving layer disposed on the substrate, and comprising: first driving circuit groups (UC1, UC2) each comprising N first pixel driving circuits (CK1 to CK32) and photo pixels (HX1 to HX4), wherein N is a natural number and each of the photo pixels (HX1 to HX4) comprises a photo driving circuit (PK1 to PK4) and a photo sensor electrically connected to the photo driving circuit (PK1 to PK4); a display element layer disposed on the driving layer, and comprising first display element groups (UP1, UP2) each comprising N first display elements electrically connected to the respective N first pixel driving circuits (CK1 to CK32); and second driving circuit groups (UC3, UC4) comprising N second pixel driving circuits, first driving circuit groups (UC1, UC2) each comprising N first pixel driving circuits (CK1 to CK32) and photo pixels (HX1 to HX4), wherein N is a natural number and each of the photo pixels (HX1 to HX4) comprises a photo driving circuit (PK1 to PK4) and a photo sensor electrically connected to the photo driving circuit (PK1 to PK4); a display element layer disposed on the driving layer, and comprising first display element groups (UP1, UP2) each comprising N first display elements electrically connected to the respective N first pixel driving circuits (CK1 to CK32); and second driving circuit groups (UC3, UC4) comprising N second pixel driving circuits, wherein minimum distances between first color display elements included in the plurality of first display elements, which are measured in a first predetermined direction in a plan view, are substantially the same, wherein a distance between two first pixel driving circuits (CK4, CK9) of the N first pixel driving circuits (CK1 to CK32) adjacent to each other in a second predetermined direction with a photo pixel of the photo pixels (HX1 to HX4) therebetween in the plan view is larger than a distance between two other first pixel driving circuits (CK3, CK4) of the N first pixel driving circuits disposed in the second predetermined direction, and wherein the each display element layer further comprises N second display elements electrically connected to the N second pixel driving circuits, wherein a display area where an image is displayed and a non-display area adjacent to the display area are defined on the display device, wherein the display area comprises a normal display area and a light sensing area for sensing a user's input by an incident light, wherein the first driving circuit groups (UC1, UC2) and the first display element groups (UP1, UP2) are disposed in the light sensing area in the plan view, wherein the second driving circuit groups (UC3, UC4) and the second display element groups (UP3, UP4) are disposed in the normal display area in the plan view, characterised in that an area which each of the N first pixel driving circuits (CK1 to CK8) occupies is smaller than an area which each of the N second pixel driving circuits occupies (CK17 to CK24).