Do France passport holders need a visa to visit SI?

No visa. As an EU citizen, a French passport holder can travel to Slovenia visa-free with no time limit, using only a valid passport or national ID card. France and Slovenia are both EU member states and members of the Schengen Area. Under the EU right to freedom of movement, French citizens do not need a visa to enter Slovenia for tourism or any other purpose, and there is no 90-day cap on their stay. They may travel on a valid French passport or a valid French national identity card. The Schengen 90/180 short-stay rule and the upcoming ETIAS travel authorisation apply only to visa-exempt non-EU nationals, not to EU citizens such as the French, so neither applies here. Because France and Slovenia are both inside Schengen, there are normally no systematic passport checks at the internal border, though spot identity checks can occur and temporary internal border controls may be reintroduced in exceptional circumstances. For stays of longer than three months, an EU citizen should register their residence with the Slovenian authorities, but no visa is ever required.