The rocker died in December at the age of 74 after a battle with lung cancer. Hundreds of thousands of people paid homage in a memorial service to the man who sold more than 100 million records in a nearly 60-year career.
French media estimates of his wealth vary wildly, with some saying it may be much lower than reported because of debts.
While the details of Hallyday's will have not been made public, the lawyers said it appeared to leave everything to his fourth wife Laeticia, 42, who married Hallyday when she was 21.
Hallyday's actress daughter Laura Smet, 34, and singer son, David Hallyday, 51, took legal action, asking for the estate to be frozen.
The court accepted that but rejected their demand to have a say on a posthumous Johnny Hallyday album which is likely to be a huge seller.
($1 = 0.8118 euros)
(Reporting by Emmanuel Jarry; Writing by Ingrid Melander; Editing by Robin Pomeroy)