Biomass pyrolysis experiments with iron oxide-based oxygen carrier for Biomass Direct Chemical Looping (BDCL) were carried out in order to understand pyrolysis behavior and oxygen carrier performance in a reducer. Biomass was used as feedstock in these experiments, and the effect of direct injection of feedstock to the reducer on oxygen carrier behavior associated with biomass pyrolysis was evaluated. In the experiments, the oxidizing and tar cracking abilities of different phases of iron oxide oxygen carrier were evaluated by measuring the produced gas composition and carbon deposition on the oxygen carrier. The volume and composition of produced gas varied according the iron oxide phases, and Fe2O3 composite showed the strongest oxidizing power, while FeO composite proved to have cracking ability of biomass tar components. Carbon deposit, on the other hand, was observed on the oxygen carrier, and increased in the order of FeO > Fe3O4 > Fe2O3, regardless of the reaction temperature.