A walk-behind self-propelled working machine includes a main body, an operation switch, and a handle device. The main body includes a moving assembly and a drive motor. The operation switch is connected to the drive motor. The handle device is connected to the main body and includes an operation member, a connecting rod, and a sensing device. The operation member includes a gripping portion for a user to hold. The connecting rod is connected to the main body. The sensing device is configured to sense a thrust that is applied to the handle device to drive the walk-behind self-propelled working machine and further includes a pressure sensor and a pressing member. When the gripping portion receives the thrust, the pressing member applies a force along a preset straight line to the pressure sensor to drive the pressure sensor to deform.