The Ligier JS1 was a racing sports car built by Ligier in 1969, and used in 1969 and 1970 sports car racing.
The JS1 was the first car built by Ligier. Guy Ligier thought of the idea of creating a sports car based on the Porsche 911 as early as 1968, and the project was started in 1969 by former Renault engineer Michel Tetu.
The JS1 was presented in September 1969 at the Paris Motor Show. The car was a mid-engine racing car with a tube frame. It was initially fitted with a 1.6-litre Cosworth engine capable of producing 220 bhp of output, but it was replaced in 1970 by an FVC unit, also by Cosworth, that generated 240 bhp. The car's fiberglass body was designed by Italian automobile designer Pietro Frua.
Guy Ligier won while racing the JS1 in Albi and Montlhéry in 1970 before competing in the 24 Hours of Le Mans race that year. This race marked the entry of the Ligier racing team into international motorsport. Ligier and his co-driver, Jean-Claude Andruet, qualified for thirteenth place at the race and eventually managed to rank in the top ten, but had to withdraw after about eight hours because of persistent problems with the distributor.
Two Ligier J1 cars were used for the 1970 Tour de France Automobile, both equipped with new engines. One vehicle received a 2.6-litre V6 engine from a Ford Capri, while the second car was fitted with a 2.4-litre Weslake unit. Both cars ended up dropping out of the race.
The JS1 was replaced by the JS2 in 1970. A restored example is often shown at events for historic racing cars.