PURPOSE: To make it possible to detect the trouble of a rain gauge, by arranging a detection turnover measure to the lower part of a turnover measure and utilizing that the turnover direction of the turnover measure is different from that of the detection turnover measure when the turnover measure performs no predetermined turnover operation.

CONSTITUTION: A turnover measure 3 constituted of measure parts 3A, 3B is mounted to a container 1 so as to be swingable around a fulcrum 4. A detection turnover measure 10 has the almost same shape as the turnover measure 3 and arranged under the turnover measure 3. When the turnover measure 3 is normally operated, for example, the measure part 3B receives rainwater and, when a predetermined amount of rainwater is accumulated, the measure part 3A is turned over to the side of the measure part 3B. At this time, a switch (S)7 is turned ON and a counter 21 counts that the measure 3 was turned over once. The rainwater drained from the measure part 3B is flowed in a detection measure part 10B and a detection circuit 15 comes to a closed state. When the turnover measure 3 is out of order, for example, even if a predetermined amount of rainwater is accumulated in the measure part 3A, no turnover is generated and rainwater is overflowed to be made to flow in a detection measure part 10A. At this time, the circuit 15 is opened and the trouble of a rain gauge 20 can be detected.