No, you don't need to have a visa. You'll need to bring the following:
(1) passport valid for at least 6 months
(2) original H1-B approval (I-797)
When you enter Canada, make sure you do not surrender you current I-94. You'll need it to come back into the U.S.
You do need a visa from the Canadian consulate to enter Canada - assume you know this already.