An electronic device includes a first and second housing, a sensor module, and a hinge. The hinge includes first and second rotary members, a first arm rotatable about a first arm shaft, operating in conjunction with rotation of the first rotary member, a second arm rotatable about a second arm shaft, operating in conjunction with rotation of the second rotary member, and a magnet assembly disposed on at least one of the first arm member or the second arm member such that at least a portion of the magnet assembly faces the sensor, wherein a distance between the magnet and the sensor is changeable based on rotation of the first and second housing.