It's for everybody.
Pitchfork recounts Pharrell's awkward interview with BBC's Channel 4 News, in which the singer stops short of calling himself a feminist:
"I've been asked if I'm a feminist. I don't think it's possible for me to be that. I'm a man. I mean... it makes sense up until a certain point, you know?"
To be fair, there's been some controversey over men calling themselves feminists. But feminism is a movement to end sexist exploitation, not just a title. Feminist writer bell hooks wrote a whole book called "Feminism is for Everybody." Worth a read.