When a pressure of a breath is kept to fall within a valid range, a CPU of a breath alcohol measuring apparatus updates a breath amount accumulation value that is an accumulation value of the amount of the breath blown into a mouth piece; when the breath pressure reaches the range outside the valid range, the CPU resets the breath amount accumulation value; and when the breath amount accumulation value reaches a valid breath amount, the CPU measures the alcohol concentration by an alcohol sensor. A breath pressure display portion is arranged at the position that can visually be recognized by a to-be-measured person who is blowing into the mouth piece.