This paper provides an convergence analysis of Toe method for 3D eddy-current problems by finite element approximation using ungauged electrical vector potential. Error estimates in finite time are given. And it is verified that provided the time-stepsize δt is sufficiently small, the proposed algorithm yields yields for finite time T an error of O(h+δt) in the L^2-norm for the electric field E =ρ↓Δ×T,where h is the mesh size.