According to one embodiment, a sensor includes a stage, a driver, and a detector. The stage includes a first portion and a second portion. The driver is configured to rotate the stage. A rotation axis of the stage passes through the first portion and is along a first direction. A second direction from the first portion to the second portion crosses the first direction. The second portion is configured to rotate along a circumferential direction with the rotation axis as a center when the stage rotating. The detector is provided at the second portion. The detector includes a first detection element configured to detect a first acceleration including a component along the second direction, and a second detection element configured to detect a second acceleration including a component along the first direction.