The defender has been out of action since the start of March with a hamstring problem.
Despite Jagielka's recent return to training, Martinez admits that he is not yet ready to go back into the team.
"Phil is very much fully fit from a medical point of view," the Spaniard is quoted as saying by the Liverpool Echo.
"He's not too far away and he's been working really well this week. But, at the moment, we have the same squad as we had at Sunderland.
"Phil is our club captain and as soon as he's ready he'll go straight back into the team. We need him immensely."
Everton are currently in fourth place in the Premier League table with five games left to play this season.