  We consider bipartite quantum state discrimination using
positive-partial-transpose measurements and show that minimum-error
discrimination by positive-partial-transpose measurements is closely related to
entanglement witness. By using the concept of decomposable entanglement
witness, we establish conditions on minimum-error discrimination by
positive-partial-transpose measurements. We also provide conditions on the
upper bound of the maximum success probability over all possible
positive-partial-transpose measurements. Finally, we illustrate our results
using examples of multidimensional bipartite quantum states.
