Given any quantum cluster algebra arising from a quantum unipotent subgroup of symmetrizable Kac-Moody type, we verify the quantization conjecture in full generality that the quantum cluster monomials are contained in the dual canonical basis after rescaling. FAN QIN 6.5. Criteria for the existence of the common triangular bases 40 7. Prerequisite for quantum unipotent subgroup 43 7.1. Quantized enveloping algebras 43 7.2. Quantum unipotent subgroups 47 7.3. Dual canonical bases 50 7.4. Subalgebras and unipotent quantum minors 51 7.5. Localization 52 8. Cluster structures on quantum unipotent subgroup 53 8.1. CGL extension 53 8.2. Quantum cluster structure 55 8.3. Quantum cluster variables 59 9. Dual canonical bases are common triangular bases 61 9.1. Parametrization 62 9.2. Integral form 64 9.3. Localization and the initial triangular basis 66 9.4. Twist automorphism 67 9.5. Consequences 70 References 71 1 The conjecture was called the quantization conjecture by Kimura after the works [GLS11, GLS12] on (classical) unipotent subgroups. 2 The matrices P E,ε and P I uf F,ε are denoted by F ε and E ε in [Kel12, Section 5.6][BZ05, (3.2) (3.3)] respectively.