Richard Leonard Wright, 49, appeared in provincial court in Charlottetown.
RCMP Cpl. Daniel D'Amour says Wright, who is from the Hunter River area, is accused of making repeated threats of bodily harm against Premier Wade MacLauchlan online.
He wouldn't reveal which social media site was allegedly used or the nature of the threats made this month.
D'Amour says police searched Wright's home on Wednesday and seized three rifles, a shotgun and marijuana.
Wright is also charged with possessing firearms without a permit and possession of marijuana.
Crown attorney Valerie Moore says Wright was remanded and will be back in court Monday.
MacLauchlan was sworn in as premier on Monday following the resignation of Robert Ghiz.