A man of height 6m observes his image to be 2m height and erect, then the mirror used is 

$\text{we\hspace{0.17em}know\hspace{0.17em}M}=\frac{\text{size\hspace{0.17em}of\hspace{0.17em}image}}{\text{size\hspace{0.17em}of\hspace{0.17em}object}}$

$=\frac{2}{6}=\frac{1}{3}=0.33$

$\text{M}<\text{1}$

 image is smaller than the object. So image is erect. So the mirror used is convex mirror.