The hearing was held behind closed doors, as ruled by the judge, who will make a statement later.
A minute's silence was held at 1200 (1000 GMT) to remember the victims.
Mr Breivik, 32, has admitted carrying out a bombing in Oslo, and a massacre on an island youth camp, killing at least 93 people in total.
He is said to be linked to far-right groups and to have spent years planning the attacks, about 9 years.
At least 96 people were injured in the attacks. But Oslo police have said the death toll from the shooting spree on the island could be revised downwards from the current 86, based on the information now available.
Mr Breivik said before the court hearing he would explain his actions to the court. Earlier, he described the attacks as "gruesome but necessary".

have been calls for a media blackout of the trial so as not to give Mr Breivik a platform for his views.
Judge Kim Heger ruled on Monday's hearing: "It is clear that there is concrete information that a public hearing with the suspect present could quickly lead to an extraordinary and very difficult situation in terms of the investigation and security."
The hearing lasted about 40 minutes. Television pictures showed what appeared to be Mr Breivik being driven away in a convoy of vehicles.
Under Norwegian law, Mr Breivik faces a maximum of 21 years in jail if convicted, although that sentence can be extended if a prisoner is deemed a threat to the public.
Police said that while the suspect had admitted the killings, he had not accepted criminal responsibility for them.
His lawyer, Geir Lippestad, told Norwegian media on Sunday: "He thought it was gruesome having to commit these acts, but in his head, they were necessary.
"He wished to attack society and the structure of society."
Still pictures of the suspect, wearing a wetsuit and carrying an automatic weapon, appeared in a 12-minute anti-Muslim video called Knights Templar 2083, which appeared briefly on YouTube.
1,500-page document written in English and said to be by Mr Breivik - posted under the pseudonym of Andrew Berwick - was also put online hours before the attacks.
The bomb in Oslo targeted buildings connected to Norway's governing Labour Party, and the youth camp on Utoeya island was also run by the party.
At 1200 local time on Monday, Prime Minister Jens Stoltenberg, at Oslo University, said: "In remembrance of the victims... I declare one minute's national silence."
Thousands of people stood around a carpet of flowers at Oslo cathedral.
One Oslo citizen, Sven-Erik Fredheim, told Reuters: "It is important to have this minute of silence so that all the victims and the parents of the families know that people are thinking about them."
It was reported on Monday that Crown Princess Mette-Marit's stepbrother, Trond Berntsen, an off-duty police officer, was among those killed at the youth camp. He was the son of Mette-Marit's stepfather, who died in 2008.
A minute's silence was held in Norway to remember the victims of the attacks
In France, police are searching Mr Breivik's father's home in Couranel in the south of the country, although they have not commented on the operation. Jens Breivik is reported not to have been in touch with his son for many years.
Bodies of those killed on the island were moved to a morgue in Oslo on Sunday.

More details have emerged about the killings and the police operation which led to Mr Breivik's apprehension.
Police said officers trying to get to the island had been delayed because they had difficulty finding a suitable boat to take them there, and there were no police helicopters close enough.
The gunman was arrested an estimated 90 minutes after the massacre began. Police say he still had a lot of ammunition, and hospital sources said he had used dum-dum bullets, designed to disintegrate inside the body and cause maximum internal damage.
One of the first victims on the island was an off-duty police officer who had been hired by the camp organisers to provide security, Reuters news agency reported authorities as saying.
At least seven people were killed in the bomb attack on the government quarter in Oslo. Soon afterwards, 85 people were shot dead as the gunman, dressed as a policeman, ran amok on the nearby island of Utoeya. An 86th victim from the island shooting died in hospital on Sunday.
At least four people from the island camp shooting are yet to be found; it is thought some may have drowned after swimming out into the lake to escape the hail of bullets.
In Oslo, police said the death toll could rise further as bodies were in buildings damaged by the bomb, but still too unstable to search.
Police say they are not searching for a second attacker, but have not ruled out more people being involved, after eyewitness reports suggested a possible second shooter.

BBC