He has the Foxes in contention for promotion to the Premier League this season, with his side currently in the Championship play-off places after a season-best run of eight games without defeat.
Mandaric is confident Pearson will not be lured away by another club and believes a new deal will be concluded soon.
"I am always confident Nigel will not leave," Mandaric told BBC Radio Leicester. "As for the legality of the deal, we are working on that as well. And before the season is finished - well before it is finished; I'd say the next 30 days or so - we will sort it out.
"We are in contact and we have dialogue. It is really a rolling contract so when the year is finished there is another year coming. We are trying to do something more but Nigel is not concerned, it is not an issue."
Pearson, meanwhile, has been nominated for the Championship manager of the month award for February.
Pearson saw his side go unbeaten during the month as the Foxes won four and drew three of their seven league fixtures.
The 3-0 home win over East Midlands promotion rivals Nottingham Forest at the weekend was arguably the pick of their February results, although Pearson's side also thrashed Scunthorpe 5-1 at home and won 2-1 at play-off chasing Blackpool.
Coventry boss Chris Coleman, Reading's Brian McDermott and Swansea manager Paulo Sousa are also in the running for the award.
The winner will be announced at Saturday lunchtime ahead of the trip to Hillsborough to face Sheffield Wednesday.
Coca Cola Ch'ship Promotion 09/10 Win Outright: Leicester 9/2