Quebec provincial police said Jean-Philippe Leblanc-Pare, 29, was arrested in Trois-Rivieres on Sunday.
Officers searched his home and seized material after the threats were allegedly made Saturday in an Internet posting on YouTube.
Leblanc-Pare was freed under several conditions following his arraignment on Monday.
Last December, Trois-Rivieres resident Daniel Brosseau was arrested after allegedly making threats against Marois on Facebook.
Marois was also the target of an attack the night she became premier in September 2012.
A gunman attempted to storm the PQ victory rally where Marois was speaking and shot two people, killing one of them.
Richard Henry Bain is awaiting trial on 16 charges, including first-degree murder and attempted murder.
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