To provide a filter element cleaning apparatus effectively cleaning a filter element attached with oil fouling.

The cleaning apparatus for cleaning the filter element removing foreign matters by filtering oil for equipment like the hydraulic control system of a power generator includes: a first cleaning tank 12 storing a weak alkaline cleaning agent solution 16; a second cleaning tank 22 allowing the communication of the weak alkaline cleaning agent solution 16 stored in the first cleaning tank 12 therewith via a through-hole 24 in the first cleaning tank 12 ; and an ultrasonic wave generation means 32 imparting ultrasonic vibration to the second cleaning tank 22.