Disclosed are a wearable device including a modular functional block and a method for extending a function of a wearable device using a modular functional block. The wearable device including the modular functional block according to an embodiment of the present invention includes a plurality of functional blocks that are removably fastened to a strap connected to a main block of the wearable device. Here, a processing block of at least one of the main block and the plurality of functional blocks recognizes a mounting state of each of the other functional blocks, and generates application information provided in a combination of the functional blocks fastened to the strap.