Alcázar de San Juan is primarily a railway junction — one of the busiest in Spain — and the easiest way to arrive is by train. The station connects Madrid Atocha (about 90 minutes by regional express) with cities to the south and east: Alicante, Albacete, Valencia, and Ciudad Real. If you are travelling by train between Madrid and the Mediterranean coast, Alcázar is on the main line.
By car it is about 150 km southeast of Madrid on the A-4 (formerly the N-IV), the main road to Córdoba and Cádiz. The town makes a logical lunch or sightseeing stop on a longer drive. There is no shortage of parking in the centre, and the historic core is small enough to cover in an afternoon.