Answer
False, change it to
"Irrational numbers can be positive or negative."
Work Step by Step
$\pi, \sqrt{2}, \sqrt{3}$ are all positive irrational numbers,
and
$-\pi, -\sqrt{2}, -\sqrt{3}$ are all negative irrational numbers,
so, the statement is false.
To make it true, we could change it to
"Irrational numbers can be positive or negative."