A lubricating oil manufacturing device (10) is characterized by being provided with: a mixing tank (20) for mixing a lubricating oil, the mixing tank (20) being provided with a stirring means (23) and a temperature adjustment means (24), and a lubricating base oil and an additive being introduced into the mixing tank (20); a reservoir tank (30) for storing the lubricating oil for which mixing is completed; and a filling machine (40) for filling a container with the lubricating oil stored in the reservoir tank (30); the reservoir tank (30) being positioned below the mixing tank (20), and the filling machine (40) being positioned below the reservoir tank (30).
