Portugal's hopes of winning the tournament in France rest to a large extent on the fitness of the Real Madrid forward who had muscular problems at the end of the season yet still helped his club beat Atletico Madrid in the Champions League final.
Ronaldo is set to start in Portugal's warm-up against Estonia in Lisbon on Wednesday night.
"He is very well physically, mentally and in terms of morale," Santos was reported as saying in Spanish sports magazine Marca.
"You will see it in the game (on Wednesday). He is in the same condition as any other player."
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Ronaldo joined his national team on Sunday, having missed out on Portugal's friendly last week at Wembley where they lost 1-0 to England.
He was bothered by tendonitis two years ago and was not at his best at the World Cup, where Portugal failed to go beyond the group stages.
Ronaldo, who scored 51 goals in 48 games in all competitions for Real this season and had the decisive spot-kick in the Champions League final win on penalties, is desperate to win a title with Portugal.
"He is really motivated," Santos said. "He was extremely motivated to win the Champions League and he is even more so now because the European title is his ambition. He is ready to take Portugal to such an important success."
Ronaldo, 31, was close to winning a trophy at Euro 2004 but Greece beat Portugal in the final. The Portuguese reached the semi-finals four years ago but were eliminated by Spain on penalties.
Portugal begin their Euro 2016 campaign, against Iceland, on June 14 in Marseille. They also take on Austria and Hungary in Group F.
(This story corrects headline to read Portugal coach)
(Reporting by Adriana Garcia; Editing by Robin Pomeroy)
