A cantilever probe card device and an elastic probe thereof are provided. The elastic probe includes a soldering segment, a testing segment, two outer elastic arms spaced apart from each other. The testing segment is spaced apart from the soldering segment along an arrangement direction, and has a needle tip, an outer edge, and an inner edge that is opposite to the outer edge. Each of the two outer elastic arms has two end portions respectively connected to the soldering segment and the inner edge of the testing segment. Moreover, one of the two outer elastic arms adjacent to the needle tip is defined as a first outer elastic arm, and another one of the two outer elastic arms is defined as a second outer elastic arm. Specifically, a length of the first outer elastic arm is greater than a length of the second outer elastic arm.