PURPOSE: To make the cause of trouble judgeable at once when a gear pump is stopped, by installing a vibro-sensor setting part, for setting up a sensor to detect the vibration, in a casing of the gear pump.

CONSTITUTION: In a casing 1 of a gear pump G, there are projectingly provided with a vibro-sensor setting boss 14 and each of temperature sensor setting bosses 15, 16 at the outside of a jacket forming panel P3, while a vibro-sensor Sv is set up in a concave vibro-sensor setting part 14a of the boss 14 and each of temperature sensors ST, ST' in respective hole-form temperature sensor setting parts 17, 18 reaching to both bearings 4, 5 from these bosses 15, 16, respectively, and each detected output is put on a record. When the gear pump G is stopped for some cause of other, a record just before the happening is checked, whereby whether it is caused by gears 2, 3 biting something foreign substances or seizure or binding of the bearings 4, 5 is made quickly judgeable. Thus, a proper step at time of gear pump stoppage is speedily performable.