Through the present invention, a prepreg having good appearance and the desired characteristics is manufactured without a reduction in productivity when the prepreg is manufactured using a resin varnish having various characteristics. In a substrate conveyance path (13) in a prepreg manufacturing device (1), a substrate (A) is immersed in a resin varnish (H) in a vat (10), excess resin varnish (H) on the substrate (A) is scraped off by a scraping roller (11) above the vat (10), and the substrate (A) can then be dried by a drying device (12). The prepreg manufacturing device (1) is configured so that it is possible to adjust the distance (D1) from the liquid surface of the resin varnish (H) in the vat (10) to the scraping roller (11) and the distance (D2) from the scraping roller (11) to the drying device (12) on the substrate conveyance path (13).