A quality estimation device (1) includes: a first acquisition unit (111) configured to acquire first information (51) pertaining to the positioning of a worker (W) executing a work step included in a process for manufacturing a product on a production line; a second acquisition unit (112) configured to acquire second information (52) pertaining to the usage condition of a tool (T) the worker (W) uses in the aforementioned work step; an estimation unit (113) configured to estimate the quality of a product being made through the work step according to the degree to which the positioning of the worker (W) and the usage condition of the tool (T) represented by the first information (51) and the second information (52) acquired conforms to a predetermined first standard and a predetermined second standard; and an output unit (114) configured to output information pertaining to the result of estimating the quality of the product.