Providing an adequate environment for horses is important to minimize the level of stress for domesticated horses. The objectives of this study were 1) to evaluate the effect of living conditions on stress level of horses, 2) to observe the effect of one month confinement on self-maintenance behavior and stereotypic behavior of horses. The experiment was conducted at National Institute of Animal Science, Equine Field Station (Seonghwan-eup, Korea). Horses were staying in the paddock prior to the experiment. On day 1, five horses were randomly selected and housed in metal fence panels stall. Six horses remained in the same paddock. The ratio of neutrophil to lymphocyte (on day 15) and cortisol (on day 1 and 29) from stalled horses were significantly higher than horses in the paddock. Duration or frequency of self-maintenance behaviors such as feeding, drinking, resting, walking was not significantly different between day 1 and day 29. However, the frequency of urination significantly decreased (p<0.05) on day 29 compared with day 1. The frequency of stereotypic behaviors was not different between day 1 and 29. Our data indicate that horses may be more stabled when they are staying in the paddock rather than staying in the stall, but the stress level of horses in the stall during one month confinement was not effective for horses to adapt stereotypic behavior. In conclusion, providing an adequate environment and stress-less horse management techniques can minimize the stress level of horses.