The Real Madrid skipper has not played since suffering a hand injury back in January, forcing the capital club to sign Diego Lopez, who has since kept his place in the first team.
However, Del Bosque has elected to keep faith in his captain ahead of the former Villarreal man.
“We are certain he is in good form. We spoke in France and since then I haven’t spoken to him, but I’m sure he is fine. He is one of our own," the 62-year-old said at a press conference.
“We deal with some extraordinary players. We have three goalkeepers and I can’t bring any more, but we could have brought another four or five. Diego has had a superb season but we trust in Pepe Reina, Iker and Victor Valdes.
“I've said before that it’s impossible to include every player that deserves a place. Fabregas, Villa, Torres and Soldado are our four strikers.
"You could just as easily ask why we didn't include [Imanol] Agirretxe, that lad from Betis [Ruben Castro], Iago Aspas, Michu.”
Del Bosque went on to say that he is looking forward to the tournament, which kicks off on June 15.
“It’s a unique tournament with its own merits. There are not only four World champions; there are also the Olympic champions Mexico and champions of Africa, Nigeria.
"We will try and make sure we compete at the highest level. Japan are one of the teams that have progressed a lot and any of the teams could be uncomfortable opponents.”