In a televised statement, Health Minister Mohamed Nedhirou Ould Hamed said the case involved a foreigner who tested positive on Friday.
“He was immediately isolated and the state has all the means at its disposal to take care of those suffering from the virus,” the minister said.
A statement from the health ministry, also released on Friday, said the man was an expatriate who had flown into Mauritania from Europe on Monday.
He isolated himself after a friend in Europe tested positive for the virus, the statement added.
Health officials discovered he was feverish on Friday morning and he was confirmed positive for coronavirus later in the evening.
The health minister also promised, in his televised address, that the government would stop charter flights coming to Mauritania from France.
The West African state of Guinea registered its first coronavirus case on Friday too.
And Senegal, which shares a border with Mauritania, registered 11 new coronavirus infections on Friday, bringing its total number to 19.
Ivory Coast, Ghana, Burkina Faso and Nigeria have all also recently registered coronavirus cases.
Gabon, which announced its first case earlier this week, said Friday it would close schools for two weeks and stop issuing tourist visas to areas hit by the pandemic.