The 49-year-old Michel, who took over at Girona in 2021, guided them to their first Champions League qualification after the club led LaLiga for much of the 2023-24 season.
“Girona FC coach Michel Sanchez has been hospitalised due to a health problem. He is under medical observation as a precaution and is progressing favourably," the club said in a statement.
"He is receiving the appropriate care and we expect him to recover in the next few days. The coach will not be able to lead the team from the bench in tomorrow's match."
Michel said in a social media post that he was counting the days until he could get back to work.
“I will not be able to be on the bench next Saturday... I have to stop for a few days to recover and return as soon as possible," he wrote.
"I feel fine... I'm sure that this group, despite my absence, will give everything."
Girona are six points above the relegation zone in 15th place, going into the last four matches of the campaign.