Work done here is zero since there is no displacement done by the man nor change in energy.Even if the man would move the work done would be zero since the displacement would be perpendicular to the the force (the weight of the box acting downwards due to gravity..)
Work done is a scalar product of force and disp. :-
W=F.∆s= Fdscos(90) =0.
(where ∆s is displacement)