Provided is a ΔE measuring device minimizing external magnetic disturbance, more particularly, a ΔE measuring device measuring a change (ΔE) in elastic modulus under a magnetic field by removing a bias effect by the earth's magnetic field and a magnetic tool and device and using a magneto acoustic resonance method. With the ΔE measuring device, a space minimizing external magnetic disturbance using three-axis Helmholtz coils is provided and the ΔE measuring device having a plurality of coil structures is inserted into the space, thereby making it possible to minimize external magnetic field disturbance.