Cannot build: Permission denied

Hello everyone, Ive just set up Ubuntu and get toolchain:
arm-linux-gcc-4.4.3 and Qtopia 2.2.0.
So, when I build a project, I got the error: 
-bash: ./build: Permission denied

What step that I need to do?
Thank you so much.

sudo ./build

"chmod +x ./build"

Yeb, thanks you so much. the 2nd way works well.