A developer-agitating transporter includes helical blades that helically extend around a rotation shaft, the helical blades being arranged at different positions in a direction perpendicular to a longitudinal direction of the rotation shaft; and a gap portion that divides each helical blade into a first blade portion and a second blade portion, which oppose each other across the gap portion, so that the helical blade is discontinuous in a direction in which the helical blade extends. The gap portion causes the first blade portion and the second blade portion to be arranged at a certain angular interval in a circumferential direction of the rotation shaft, and at least one surface of adjacent ones of the helical blades that are adjacent in the circumferential direction of the rotation shaft has a sloped area that is sloped at an angle that changes with respect to an axial direction of the rotation shaft.