Chargois, 26, made his debut last year, posting a 4.70 ERA with 17 strikeouts and 12 walks in 23 innings. He pitched better after a rocky debut on June 11, posting a 2.82 ERA with 17 strikeouts in 22 1/3 innings after being called up again in mid-August.
Chargois is expected to close at Rochester, and the Twins want him to refine his command, as he has plus-stuff, including a fastball that averaged 96.2 mph last year.
With Chargois optioned, the bullpen is starting to take shape. Closer Brandon Kintzler, Ryan Pressly, Matt Belisle, Craig Breslow and Taylor Rogers are locks, leaving two open spots.