To provide an alarm device capable of informing a sailor existing anywhere in a cabin intuitively and intelligibly of the direction and the risk of an obstacle around own vessel.

The obstacle is expressed numerically by an obstacle detection means comprising a dangerous position detection means 101 for detecting the obstacle by using a radar detector or the like, acquiring a latitude and a longitude of the obstacle, and calculating relative speed in view of own vessel, and a relative angle detection means 102, and a risk factor k is calculated by a risk factor calculation means 103 based on the output from each means. Then, the risk factor k is compared with a threshold n, and if k is larger than n, a stereophonic sound is output by an acoustic output means using four or more speakers through a sound field generation means in a dangerous direction informing means.

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