I'm a little scared

Evelin
Ok. So my dad has been really weird. When we are in a store, he will walk behind me and then he will get closer and slightly put his hand on my butt......it has been happening a lot. I don't know if it's on accident or not.
I don't know weather to tell my mom.  When we are in the kitchen and I'm cleaning up, he will come really close to me. And I feel really uncomfortable. What should I do?