Although Tony Pulis has made his side hard to beat, they are still too near the drop zone for safety, while Ipswich can now look at making a play-off run, especially with most of their squad fit at last.
Town built a two-goal half-time lead through Jay McEveley and Jimmy Juan, and although Plymouth got one back with a brilliant Akos Buzsaky free-kick, Matt Richards' penalty sealed it.
Ipswich could have gone in front on four minutes when Romain Larrieu punched out Darren Currie's corner to Richards whose low drive went through a forest of legs, and bounced off both Larrieu and Nicky Forster before the goalkeeper grabbed it.
Tony Capaldi curled a free-kick over, Micky Evans sent a header straight at Lewis Price and Buzsaky had a shot deflected over as Plymouth enjoyed a decent spell.
It was broken on 23 minutes when Larrieu turned aside Kevin Horlock's shot but from the ensuing corner, it dropped to McEveley on the edge of the box and his low left-foot shot beat everyone for the Blackburn loanee's first Town goal.
Plymouth's struggles on set-pieces surfaced again after 31 minutes when Jason De Vos helped on another Currie corner and Juan had the easy task of heading in from close-range while unmarked.
Price saved from Buzsaky and the Plymouth dangerman sent an in-swinging corner crashing off the crossbar as Town kept the lead through to half-time.
Hasney Aljofree robbed Forster as he threatened to run clear a minute after the break, before Plymouth pulled one back on 51 minutes.
Horlock felled David Norris on the edge of the box and Hungarian Buzsaky sent a sublime curler soaring into the top right-hand corner.
Town went two goals clear again after 56 minutes with a controversial penalty when Sam Parkin headed through for Forster who rounded Larrieu and went to ground.
It looked as if he had fallen after losing control of the ball, with little contact from the keeper and Paul Connolly was booked for dissent before Richards coolly sent Larrieu the wrong way from the spot.
Buzsaky sent a thundering volley over and Nick Chadwick shot over after turning away from Richard Naylor as Plymouth tried to find a way back into the game.
Their final chance of a comeback came and went on 78 minutes when a quick free-kick saw Capaldi play in Norris, but his low drive flashed across goal with no-one able to turn it in.
Ipswich held on comfortably, and even looked like scoring more goals on the break, with Sito Castro and substitute Dean Bowditch both off target with shots from the edge of the box.
It was a good day all round for Ipswich, who had Horlock and Forster starting after comebacks from injury, while Ian Westlake completed the last 15 minutes after a two-month lay-off with an ankle ligament problem.