Rural houses are recently built using confined masonry walls. The concrete beam and column confining the wall are usually considered to resist lateral loads, such as earthquake load. The Indonesian code requires reinforcement of 12 mm diameter in each corner of the beam and column with 8 mm diameter of stirrups. Such houses are usually termed of non-engineered structures, i.e buildings which the strength is not technically calculated but is established by the communities based on their experiences. This research was aimed to relate the in plane lateral ground acceleration and the resulting lateral displacement on the top of the wall at the first fundamental frequency. As the wall occasionally breaks at certain lateral drift ratio (H/V ratio), therefore, a prediction of the maximum lateral ground acceleration of the wall due to earthquake shake may also be established. Two wall specimens were made of local masonries with dimensions of 3m x 3m and 0.15 m thick. Lateral loads were applied in several stages and ambient vibrations of the two accelerometers, mounted on the base and on the top of the wall, were also recorded in stages. The maximum lateral force prediction, calculated using allowable lateral ground acceleration, was closely approaching the experiment result and numerical calculation.