To provide a flow oil monitoring device capable of monitoring the quantity of the flow oil in a pipe by utilizing the oil flow flowing in particles at the bent part.

The flow oil monitoring device comprises a light emission device 21 for irradiating the bent part Pc formed in the pipe P of light translucency, a light receiving element 22 for receiving the light transmitted through the bent part Pc of the pipe P irradiated by the light emission device 21 and outputting signals corresponding to the light amount of receiving light, a detection signal creating process unit 100 for creating detection signal varying corresponding to the existence of the oil particles of the oil flowing through the bent part, a pulse counter 201 for counting the equivalent part existing the oil particles of the detection signal created by the detection signal creating process unit 100, and an operation process part 205 for creating the monitor information by editing the countable number obtained by the pulse counter 201.