The detention of judges Jesus Rojas Torres and Zuleima Gonzalez happened in the eastern state of Anzoategui, the National Assembly said on Twitter.
Their arrests brought to three the number of opposition-named judges being held, following the arrest on Saturday of another, Angel Zerpa.
A military tribunal on Monday ordered Zerpa be imprisoned, according to a rights group, Foro Penal, and an opposition leader, Henrique Capriles.
Prosecutors have petitioned for his release, AFP reported.
They were among 33 judges the opposition-led chamber last week named to the supreme court, creating a parallel body to the high court whose members have shown systematic loyalty to Maduro.
The supreme court and Maduro's government have said those involved in the parallel court were committing "incitement to subversion."
On Sunday, Maduro vowed that the opposition's judges would be arrested "one by one" and their assets frozen.
The wrestle over the legitimacy of the supreme court judges comes as Maduro presses on with a bid to have the constitution rewritten.
This weekend his officials are holding an election to appoint 545 people to sit on a body called the Constituent Assembly to carry out that task.
The opposition, which staged an unofficial referendum in which a third of the electorate rejected Maduro's plan, is fighting that effort, and has called a boycott of the vote.
International condemnation has also been directed at Maduro's effort, and US President Donald Trump has threatened economic "actions" if the election goes ahead.
On Wednesday, the opposition is launching a nationwide strike - its second in a week - to up the pressure on Maduro to back down.
Meanwhile, street protests against Maduro continue. In four months, more than 100 people have died during the demonstrations.