Reuben Reid's first goal of the season was enough to clinch Plymouth's first home win of the campaign.
Reid, who had an earlier effort ruled out for a foul, struck from the penalty spot on 25 minutes after Dale keeper Josh Lillis brought down Marvin Morgan.
The outstanding Conor Hourihane hit the bar from distance for Argyle, with the visitors restricted to hopeful efforts.
Rochdale were much improved after the break, with Matt Lund and Bastien Hery going close, but the home side held on.
VIEW FROM THE DRESSING ROOM
Plymouth boss John Sheridan told BBC Radio Devon:
"It's always a good habit not to concede and end up winning the game. It can only breed a bit of confidence into the players.
"It was a game of two halves but it should never have got to that. We played really well first half, we were on the front foot, caused them lots of problems and should have had the game sewed up.
"When it's 1-0 a team like Rochdale, who are very confident in the way they pass the ball still believe they've got a chance and they came back into it second half.
"Full credit to them, but I thought we just took our foot off the pedal."
Plymouth Argyle 23 McCormick 02 Berry Booked 05 Branston Booked 16 Trotman 17 Nelson 06 Hourihane 07 Alessandra 08 Boco (Blackman - 82' ) 11 Blizzard (Young - 86' ) 09 Reid (Gurrieri - 73' ) 10 Morgan Substitutes 01 Cole 03 Blackman 04 Blanchard 22 Richards 14 Young 18 Harvey 27 Gurrieri Rochdale 01 Lillis 06 Lancashire 15 Vidal 22 O'Connell Booked 25 Rose 07 Vincenti 08 Tutte (Hery - 69' ) 12 Lund Booked 16 Done Booked (Bunny - 54' ) 11 Hogan 40 Henderson Substitutes 21 Thomson 02 Rafferty 03 Bennett 05 Eastham 10 Gray 14 Hery 39 Bunny