PURPOSE: To make it speedily judgeable whether the cause is attributable to seizure or not at time of gear pump stoppage by installing a temperature sensor setting part, for setting up a sensor to detect the temperature, in each bearing of turning shafts of a pair of gears.

CONSTITUTION: Each of temperature sensor inserting bosses 15, 16 being projected to an outer surface of a jacket forming panel P2 is installed in a casing 1 of a gear pump G in a projecting manner, and there are provided with slender hole-form temperature sensor setting parts 17, 18, reaching to symmetrical bearings 4, 5 supporting turning shafts 6, 7 as one body with a pair or gears 2, 3 from this surface, in which temperature sensors ST, ST' are insertionally set up. Then, a change record of temperature by these discharge pressure and temperature sensors ST, ST' is checked, and thereby whether the cause of stopping of the gear pump G is caused by seizure of the bearings 4, 5 or the paired gears 2, 3 have bitten foreign substances is presumable. Thus, the cause of gear pump stoppage is speedily found out, and quick troubleshooting can be done in this way.