It depends by what you mean by "protect it." First, you automatically have copyright in the menu--everyone who creates something written gets copyright in it by the act of creation. However, copyright only protects the specific expression--that exact menu, and the way it's written, the font, the graphics, possibly any unusual terms or descriptions of food (which might also be protected under trademark law), such as, for example, if an ocean-themed restaurant called it's linguini "pasta tentacles." (And yes, I know that'd be an awful name--I'm not a marketer or restauranter.)However, intellectual property law, especially copyright, does not protect factual information. So another restaurant could offer the same dishes that you offer and could use your menu as an inspiration for their own offerings--to use an Italian restuarant example, you can't stop another Italian place  from offering mussels, antipasto, and a caeser's salad as appetizers, even if they looked at your menu before doing so. So you can't protect the items on your menu, but you can protect the way the menu is laid out, illustrated, the exact wording (unless it's generic working--you can't keep someone from calling ravioli "meat-stuffed pasta), etc. I.e you can protect the *menu* but not what's on it.