Battery active material, nonaqueous electrolyte battery, and battery pack

According to one embodiment, there are provided an active material for a battery having a high effective capacity, a nonaqueous electrolyte battery, and a battery pack. The active material contains a niobium-titanium composite oxide. When the active material is subjected to powder X-ray diffraction (XRD) using a Cu-Kα ray source, a peak appears in a range of 2θ = 5° ± 0.5° in the diffraction pattern.