An Interior Ministry spokesman said on Wednesday that the arrests were made across the kingdom, including Eastern province, the capital Riyadh and the holy cities of Mecca and Medina.
"The arrests were made over the last week or so," he said.
"Some of them were related to publishing the terrorists' ideas on the internet ... others were providing assistance, hideouts and financing to terrorists."
A separate statement issued by the government said eight of those detained had links to a planned attack on the Abqaiq oil plant.
The statement said the names of the suspects would not be released.
There has been a spate of attacks in Saudi Arabia culminating in last month's foiled al-Qaida attack on Abqaiq, in which two militants were killed.
The spokesman said that security forces had also seized a cache of explosives and firearms in simultaneous raids in several parts of the kingdom, but he was unable to say if the suspects had been planning new attacks.
Saudi television aired footage of the cache showing hand grenades, AK-47 assault rifles, and various firearms.
Officials say about 144 foreigners and Saudis, including security forces, and 120 militants have died in attacks and clashes with police since May 2003, when al-Qaida bombers hit three Western housing compounds in Riyadh.