Know-How Exchange : Other

Hi.I'm a freelance web designer from the philippines and I'm planning to put up an online directory website. There are existing online directories out there but mine has a twist(its a secret :)). My question is do I need to ask permission from the shops if I am going to add them? When I look at their individual websites I usually find a store locator page. One way to gather info is just visit all their sites and collect the data and consolidate them in my site. But like I said I'm not sure of the legal issues here if i do that. So, do I need to approach or talk to each and every shop If am going to add to my site? Thanks in advance.