The angle between the direction of force and the direction of displacement, for work to be negative is ${180}^{\circ }$.
$\because \mathrm{W}=\mathrm{Fs}\cos \mathit{\theta }.$

$\therefore \mathrm{W}=\mathrm{Fs}\cos {180}^{\circ }$
$=-\mathrm{Fs}\left(\because \cos {180}^{\circ }=-1\right)$
$\therefore$ Work done is negative.