To provide a bearing capacity measuring device of a hydraulic press-in machine capable of measuring a bearing capacity of the ground while pressingly placing a pile like a steel pipe sheet pile, and recording and controlling the bearing capacity on a real time basis.

A pressure converter fitting body 36 of the bearing capacity measuring device 34 of the hydraulic press-in machine is arranged at an intermediate part of a hydraulic pressure hose 30 for a first jack of the hydraulic press-in machine 10. Oil which flows in the hydraulic hose 30 and flows then into a hydraulic jack device 18 flows in the pressure converter fitting body 36. A pressure converter 38 is fitted to the pressure converter fitting body 36. The pressure converter 38 has a function that the pressure of the oil passing through the pressure converter fitting body 36 is converted to an electric current. The pressure converter 38 is connected to a strain measuring device 42. The strain measuring device 42 is connected to a printer 46, so that the pressure value etc. upon pressingly placing the steel pipe sheet pile 1 can be printed.