To provide a diaphragm, cracking-detectable before damage to the diaphragm to cause the leakage of a controlled fluid without producing an increase in cost.

The diaphragm so provided in a fluid control device as to partition a pump chamber in the fluid control device from an actuator chamber comprises a conductive member and an insulating member so covering the conductive member at both sides as to preclude the contact of the conductive member with the pump chamber and the actuator chamber, wherein a resistance value detection circuit containing the conductive member is formed.