World champions Germany are rated as narrow bookmakers' favourites to win Euro 2016, but Del Bosque fears Didier Deschamps' squad most in the competition.
The Spain boss did stress the tournament is wide open and that all seeded sides, as well as the majority of the 24 teams playing in France, would fancy their chances.
"There are many rivals and there is no clear favourite," Del Bosque told Gazzetta dello Sport ahead of his team's friendly in Italy on Thursday.
"If I have to only say one name, I would say France because they are playing at home.
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"All the seeded teams can win. One thinks of Italy, Belgium, England, Germany, France, Spain, Portugal, but it sure appears that someone else will find the right form.
"It is a short tournament with 24 teams, so it will be unpredictable."
On the match with Antonio Conte's team – who they beat in the Euro 2012 final – Del Bosque spoke positively about Spain's opponents.
He added: "No, Italy have not found a world-class striker, however, but they remain a difficult team to face.
"Italy's defensive structure is that of his [Conte's] Juventus side and that is the basis of everything. Frankly, I do not see big differences between this and [Cesare] Prandelli's Italy."