PURPOSE: To preserve safety of a user by providing a water mask with an electronic device thereby to indicate environmental values, time or the like inside of the water mask.

CONSTITUTION: A water mask 9 is provided with a semiconductor pressure sensor 10, a luminous indicator 11 and an electronic device 12 such as detecting circuit or the like at the upper portion of a rubber frame thereof, and with a battery bag 14 on a strap 15. A nozzle 13 serves to transmit an outside pressure to the semiconductor pressure sensor 10, and owing to a signal processing of the sensor 10, a depth of water may be indicated by an indicator 11. Accordingly, a user may read the depth of water only by turning his eyes slightly upwardly as depicted by a dotted line. Further, an alarm device 16 serves to indicate a warning and sound an alarm at a set value in response to a submergence time and a decompression time.