Key switch and keyboard

A key switch, comprising:

• a movable part configured to be moved by a pressing operation;
• a support mechanism that movably supports the movable part;
• an electrical connector including multiple pairs of contacts of upper electrodes and lower electrodes;
• and
• a disc spring that is disposed between the movable part and the electrical connector and configured to be elastically deformed by movement of the movable part and to press the electrical connector, wherein
• the multiple pairs of contacts are provided for one movable part;
• when the disc spring is deformed by the movement of the movable part, the disc spring is configured to simultaneously press the multiple pairs of contacts provided for the corresponding movable part;
• and
• the multiple pairs of contacts include a first contact pair including a first upper contact and a first lower contact that have a first semicircular shape and a second contact pair including a second upper contact and a second lower contact that have a second semicircular shape that is symmetric to the first semicircular shape, the first contact pair constituting a part of a first electric circuit and the second contact pair constituting a part of a second electric circuit that is independent of the first electric circuit.