To provide a fall-sensing device which is provided with a small acceleration detection means which can be implemented with simple computation and improves uniformity of a small acceleration detection effective threshold value to a direction of an acceleration vector.

The small acceleration detection means generates detection output when the absolute values of acceleration values of three axes which a three-axis acceleration sensor detects are each at most a first threshold value, and the sum of the absolute values of the acceleration values of the three axes which the acceleration sensor detects is at most a second threshold value which is at least 1.5 times and at most 2 times the first threshold value.