A dosing device (1) is used for dosed administration of a free-flowing product together with a free-flowing carrier medium. A storage container (2) for the product has at least one access opening (3). A dosing-piston body (4) can be moved sealingly in the storage container (2) between a starting position and at least one dosing position. The dosing-piston body (4) is hollow and frees a passage between a piston-body opening, facing the at least one access opening (3), and an externally accessible suction opening (21) of the dosing-piston body (4). The dosing-piston body (4) has an outer dosing sleeve (5) and an inner, hollow piston body (6). The latter is rotatable in the dosing sleeve (5) about a longitudinal axis (7). The dosing sleeve (5) has, at the bottom, an eccentric dosing-sleeve opening (11). The inner piston body (6) has, at the bottom, an eccentrically arranged piston-body opening (14). In a position of relative rotation of the dosing sleeve (5) with respect to the inner piston body (6) for passage, a passage is created between the interior of the storage container (2) and the interior of the inner piston body (6). In a position of relative rotation for closure, this passage is closed. The result is a user-friendly and compact dosing device.