Abstract: A body movement detection sensor includes a sensor section having a piezoelectric film, a right belt member, a left belt member, and an engagement member configured to engage the right and left belt members. In the body movement detection sensor, the piezoelectric film exhibits piezoelectric effect in a length direction, the right belt member and the left belt member have substantially no elasticity, the body movement detection sensor further includes an elastic sheet directly or indirectly connected to the right belt member and the left belt member, the piezoelectric film and the elastic sheet are arranged substantially without irregularities when viewed from a side, and the elastic sheet has a maximum amount of expansion larger than an amount of change of a thorax during breathing and has a length equal to or smaller than one-sixth of a total length of the right belt member and the left belt member.