1. A mobile terminal for performing a chat, the mobile terminal comprising: a wireless communication unit configured to perform the chat with at least one chat party using an instant messaging service; a display unit configured to display at least one chat window including a chat content display region and a chat content input region while the chat with the at least one chat party is ongoing, wherein the chat content display region displays at least one message previously transmitted to the at least one chat party and the chat content input region displays at least one new message that is to be transmitted to the at least one chat party; a user input unit configured to receive a text data by typing input; and a controller configured to: control the wireless communication unit to perform the chat with a first chat party, control the display unit to display a first chat window when the first chat party is selected, control the wireless communication unit to perform the chat with a second chat party when the second chat party is selected, control the display unit to display a second chat window including a chat content display region and a chat content input region while the chat with the second chat party is ongoing, control the display unit to display a lastly transmitted message of a plurality of previous chats with the first chat party in the chat content input region of the second chat window for transmission to the second chat party, and search at least one transmitted message of the chat with the first chat party via initial character search based on the text data received via the user input unit and control the display unit to display a result of the search in the chat content input region of the second chat window instead of displaying the lastly transmitted message when the text data is received via the user input unit.