The young man was found in the city of Kesennuma, in Miyagi prefecture - one of the hardest-hit regions - Japan's NHK broadcaster reported.
The quake and the tsunami it triggered have killed at least 7,200 people. About 11,000 more remain missing.
The disaster also damaged a nuclear plant raising fears of radiation leaks.
The survivor, identified as Katsuharu Moriya and aged in his 20s, was rescued from a wrecked house on Saturday, NHK reported.
He is said to be in a stable condition but was in shock and unable to speak.
Earlier, it had been believed that heavy snowfalls had all but ended hopes of rescuing anyone from the rubble.
Millions of people have been affected by the 9.0-magnitude quake and tsunami.
Many survivors have been left without water, electricity, fuel or enough food; hundreds of thousands are homeless.
Prime Minister Naoto Kan said in a television address on Friday: "We will rebuild Japan from scratch. We must all share this resolve."
He said the natural disaster and nuclear crisis were a "great test for the Japanese people", but exhorted them all to persevere.
Add new comment