Recently, the magnetostrictive microcantilever (MSMC) as a high performance biosensor platform was introduced. The MSMC is a wireless acoustic wave (AW) sensor and exhibits a high Q value. More importantly, the MSMC works well in liquid. In this paper, the detection of Bacillus anthracis spores using MSMCs with filamentous phage as the bioprobe is reported. The phased-coated MSMC biosensors were exposed to cultures containing target spores with increasing concentrations ranging from 5 × 104 to 5 × 108 spores/mL. By monitoring the shift in the resonance frequency of the MSMCs, the spores were detected in a real-time manner and a detection limit of 105 spores/mL was obtained for the MSMCs used in this research. Higher sensitivity is expected for the MSMCs with smaller size.