Ernest Bai Koroma said the epicentres of the outbreak in the east would be quarantined and asked the security forces to enforce the measures.
The UN says 729 people in West Africa have died of Ebola since February – 233 of them in Sierra Leone.
This includes Dr Sheik Umar Khan who led Sierra Leone’s fight against the virus. His funeral is on Thursday.
As part of the new measures to contain the viral haemorrhagic fever, travellers at airports will have to wash their hands with disinfectant and have their temperatures checked, President Koroma said in a statement.
All deaths must also be reported to the authorities before burial, he said.
His measures – to remain in place for between 60 and 90 days – follow tough anti-Ebola policies introduced this week in neighbouring Liberia, where schools have been closed and some communities are to be quarantined.
Both President Koroma and his Liberian counterpart Ellen Johnson Sirleaf have cancelled visits to Washington for the US-Africa summit next week because of the crisis.
Meanwhile, Ethiopia is to begin screening all passengers arriving from West Africa and Kenya has stepped up surveillance at all ports of entry.
In a statement, Ethiopian Airlines said ground and on-board staff would have also been sensitised on how to handle suspected cases of the virus.
However, the International Air Transport Association (IATA) said on Thursday that it was not recommending any travel restrictions or border closures after consulting the World Health Organization, according to Reuters.
Any risks would be low in the rare event of an Ebola sufferer travelling by air, it adds.
Earlier this week, two airlines – Asky, a regional carrier, and Nigeria’s Arik Air – suspended flights to Liberia and Sierra Leone.
Sheik Umar Khan, 39, was a leading doctor specialising in viral haemorrhagic fever who died after contracting Ebola while treating patients. When it was announced that he had been infected, the health minister called him a “national hero” for his tireless work.
“He’d become a real figurehead for the Ebola response so there’s a sense of deep sadness in what’s a very small community here in Freetown,” his colleague Dr Oliver Johnson said.
“When the news first broke that he was sick, I think it added to fears amongst the many doctors and nurses about treating Ebola patients. People thought, if even Dr Khan can get sick, then any of us can get sick.”
The outbreak – the world’s deadliest to date – was first reported in Guinea in February. It then spread to Liberia and Sierra Leone, and a person who travelled from Liberia to Nigeria died of the virus shortly after arriving in Lagos last week.
Initial flu-like symptoms can include a sudden fever, intense weakness, muscle pain and a sore throat, and spreads through contact with an infected person’s bodily fluids.
Ebola kills up to 90% of those infected, but patients have a better chance of survival if they receive early treatment.
President Koroma said that in Sierra Leone there had been more than 130 survivors of the disease.
“This is why it is very necessary to get those with the virus to treatment centres not only to prevent others from contracting the virus, but also increasing their own chances of survival,” he said.
Symptoms include high fever, bleeding and central nervous system damage
Fatality rate can reach 90%
Incubation period is two to 21 days
There is no vaccine or cure
Supportive care such as rehydrating patients who have diarrhoea and vomiting can help recovery
Fruit bats are considered to be virus’ natural host