Abstract: A life saving device that can be attached to the body of a user including an attachment strap, a housing, an inflation sac, a rope, a pressure release device and a compressed air cylinder. The attachment strap is attached to the user's body. The housing accommodates the inflation sac, the rope, the pressure release device and the compressed air cylinder. An upper cover of the housing is popped off when the inflation sac is being inflated. The inflation sac envelops the compressed air cylinder and most of the pressure release device with a press element of the latter partly projecting from an opening of the inflation sac. When the press element is pressed, a steel ball stopping the compressed air cylinder is pushed away so that compressed air escapes from the cylinder through a tubular body and an air outlet of the pressure release device into the interior of the inflation sac to form a life ring. The rope is provided to allow the user to pull back the inflation sac if it floats away from him/her.