This paper experimentally discusses contributions of brick infills to the seismic performance of an Indonesian reinforced concrete (R/C) building, which was moderately damaged due to the 2007 Sumatra earthquakes. A brick wall was extracted from the building and was imported to Japan from Indonesia. Two R/C one-bay frame specimens were also constructed representing the first story of typical Indonesian buildings. The imported wall was installed into one of the specimens, to prepare a brick masonry infilled R/C frame. Quasi-static loading tests of both specimens, namely, bare and infilled frames were carried out to quantitatively evaluate contributions of the infill to the overall frame performance. As a result, the brick infill significantly increased the strength of total frame but decreased the ductility. This result was explained in detail based on the lateral force resisting mechanism of this kind of structure. The averaged shear strength of brick infill was evaluated as 0.73 N/mm2, which was a relatively high value. Therefore, infill walls used in the investigated building seemed to strongly contribute to prevent the building from completely collapsing during the earthquakes.