Disclosed is a method for transmitting a message in a wireless terminal. The method includes the steps of checking a size of message contents to be transmitted when the message contents are input in a message writing mode, calculating an available data attachment capacity based on the size of the message contents, photographing an image to be attached to the message with a size (e.g., a number of pixels or bytes) within the available data attachment capacity and attaching the photographed image to the message, and transmitting the message with the attached image when a transmission key is operated.