The invention NPC (Non-Player Character) relates to a battle method of monsters, moving away from the existing one-time battle can be repeated continuously combat by user selection with respect to the same NPC monster in the online game in the battle map-loading It relates to a system and method that allows. As a condition to perform a repetitive successive battles are to be victorious in the battle, and user satisfaction for it provides an interface where you can select the continuous fight makes it possible to repeatedly perform the same battle against NPC monsters. Depending on the number of consecutive battles but the difficulty of the battle Difficulty level rise due to population growth and the NPC monsters, enabling large experience acquired in a trade item ratings rise and a short time of being dropped from NPC monster. This, by the repeated continuous fight for the same NPC monsters according to the present invention allows the option of the user, hunting mopmol that pointed to an existing online games harm, caused by a useless item drop game world increases my item numbers and this according film may include DB server load increases, caused by a wide range of recyclable utilize the same NPC monsters only difficulty adjusting, such as population growth and level adjustment brings reduced development time and development cost reduction in terms of game development. Also it can have a superiority over the straight recording comparison with the user's point of view has the expectations for the achievement and drop the item to be obtained through the longline, the other user after the battle.