1. An organic EL display panel comprising: a substrate; and a bank layer on the substrate, the bank layer defining a first sub-pixel region that has an elongated shape and a second sub-pixel region that has an elongated shape and a light-emission color different from a light-emission color of the first sub-pixel region, the bank layer having an upper portion in which a plurality of concave portions are provided, wherein in a plan view of the substrate, the second sub-pixel region is adjacent to the first sub-pixel region in a direction other than a longitudinal direction of the first sub-pixel region, and when an imaginary line is drawn in a lateral direction from a center point in a longitudinal direction of the first sub-pixel region, and when, of two intersection points where the imaginary line and an edge of the first sub-pixel region intersect, an intersection point closest to one of the concave portions provided in the bank layer is defined as a reference point, a minimum distance between the reference point and an edge of said one of the concave portions closest to the reference point is shorter than a minimum distance between the reference point and an edge of the second sub-pixel region closest to the reference point.