Abstract: In this paper, relative defect and absolute defect of derivative of algebroid functions in the plane are defined . Under the conditions of N(r,\frac1W)=S(r,W),~~N(r,\frac1M)=S(r,M) and T(r,W')\sim lT(r,W),~~T(r,M')\sim lT(r,M), the relative defects on common roots of two v-valued algebroid functions W(z),M(z) with common roots are studied respectively. The results obtained generalize some results on meromorphic functions of Singh A.p..