Jamie Ward's third goal of the season did the trick in the 37th minute. The former Aston Villa starlet seized on Mickey Evans' knock-down from a Lee Thorpe free-kick, worked some shooting room in a crowded goalmouth and fired a left-foot volley into the roof of the net from ten yards.
That effort confirmed Torquay's growing superiority after Mansfield's bright start as Matt Hamshaw and Michael Boulding both went close for the Stags.
But the combination of Evans' aerial power and the pace and trickery of Ward were a constant threat throughout and, as the Stags faded, it only became a question of whether the Gulls could kill the contest off.
Twice Ward nearly stretched the lead early in the second half. He also set up Lee Mansell for a volley over, and he finally left to a standing ovation in the 72nd minute.
Mansfield boss Peter Shirtliff sent on all three of his substitutes before the 70th minute, in a vain attempt to galvanise his lightweight attack.
Town had scored 12 goals in their first seven league games, but did not hit that sort of form.
The visitors did force a series of corners in the closing stages as Torquay became jittery in defence of their narrow lead, but centre-half Thorpe and goalkeeper Nathan Abbey remained commanding figures to the end.
Ward's replacement Chris McPhee had a great chance to finish it six minutes from time, again set up by Evans, but he blazed over with only Town goalie Jason White to beat.
Torquay have now suffered only two defeats in 15 games since Ian Atkins assumed command near the end of last season.
Atkins rescued them from relegation in a dramatic turnaround in April and May, and he's now got them on the heels of the promotion chasers only four months later.