Capo 3
The chords are, for the whole song:
     C   Bm7  Em   Dm7  (G)
e|---0----2----0----1----3---|
B|---2----0----0----1----0---|
G|---0----2----0----2----0---|
D|---3----0----2----0----0---|
A|---4----2----2---------2---|
E|-------------0---------3---|


Let's go
C                  Bm7
S.I.S.T-T-T.A.R, Sistar!
                                Em
Baby stop breakin' my heart (oh no)
                              Dm7
You heard me? No more next time!
                  (G)
I hope you got that boy


And it continues like this
except for the bridge that goes with these chords:

     C    D   Bm7  Em
e|---0----1----2----0---|
B|---2----2----0----0---|
G|---0----1----2----0---|
D|---3----0----0----2---|
A|---4---------2----2---|
E|------------------0---|

      C                 D  
Oo Boy, deo joha jil surok
   Bm7               Em
Oo Boy apeun nae mameul ani neo
C                                 D
Nae mame jageun soksagim, ttaeron nareul boneun ttaddeut han nungil    
Bm7                     
Geugeo hanamyeon dwe, ojik neoman wonhae
        Em
Ajik do neoman nae mam moreu janha


Good Luck :)

Official SISTAR website: http://starship-ent.com/sistar.php