A cartridge includes: a casing for accommodating developer; a rotatable body rotatably provided at the casing; a pivot member; and a biasing member. The rotatable body is rotatable about a rotational axis, the rotatable body having an outer circumference defining a rotational path during rotation. The pivot member is disposed at the rotatable body at a position offset from the rotational axis and is pivotable about a pivot fulcrum extending in a direction parallel to a tangential direction of the rotational path. The pivot member being pivotably movable between an erect position in which the pivot member erects to form a first angle relative to the rotatable body and a collapsed position in which the pivot member pivots toward the rotatable body to form a second angle smaller than the first angle relative to the rotational body. The biasing member biases the pivot member toward the erect position.