According to one embodiment, an inertial sensor includes a base portion, a weight portion, a connection portion, and a first sensing element unit. The connection portion connects the weight portion and the base portion and is capable of being deformed in accordance with a change in relative position of the weight portion with respect to the position of the base portion. The first sensing element unit is provided on a first portion of the connection portion and includes a first magnetic layer, a second magnetic layer, and a nonmagnetic first intermediate layer. The nonmagnetic first intermediate layer is provided between the first magnetic layer and the second magnetic layer.