A display medium includes a pair of substrates, a spacer, an injection port, and an exhaust port. The pair of substrates faces to be in parallel with each other. At least one of the pair of substrates constitutes a display surface. The spacer is disposed between the pair of substrates to form a fluid chamber together with the pair of substrates. The fluid chamber encapsulates a fluid material and has a polygonal shape in a cross section taken parallel to the display surface. The polygonal shape has two acute corners each having an angle greater than 0.degree. and no greater than 75.degree.. The fluid material flows in accordance with electric fields generated between the pair of substrates to display images on the display surface. The fluid material is injected into the fluid chamber through the injection port. Air in the fluid chamber is exhausted outside the fluid chamber through the exhaust port. A distance between one of the injection port and the exhaust port and one of the two acute corners as viewed from a direction orthogonal to the substrate is equal to or smaller than 5 mm.