A working machine comprising: a prime mover; a hydraulic pump (P1, P2) to be driven by power of the prime mover to output operation fluid; a hydraulic actuator (C1-C4, C9, MR, ML, MT, AUX) to be actuated by the operation fluid outputted from the hydraulic pump (P1, P2); an operation member (19, 20) operated by an operator to change an operation extent of the operation member (19, 20); a first setting member for the operator to select one of revolution switching positions (R1-R7), each of the revolution switching positions (R1-R7) assigning a target value of the revolving speed of the prime mover; a second setting member for the operator to select one of speed switching positions (N1-N5); a storage portion to store a plurality of speed levels (HI, HI2, MID, MID2, MID3, MID4, LO), each of the speed levels (HI, HI2, MID, MID2, MID3, MID4, LO) defining a maximum value of operation speed of the hydraulic actuator (C1-C4, C9, MR, ML, MT, AUX) for a combination of selected one of the revolution switching positions (R1-R7) and selected one of the speed switching positions (N1-N5); a revolving speed controller portion configured to revolve the prime mover at the target value of the revolving speed assigned to selected one of the revolution switching positions (R1-R7); and a speed controller portion configured to increase the operation speed of the hydraulic actuator (C1-C4, C9, MR, ML, MT, AUX) as the operation extent of the operation member (19, 20) increases, and to maintain the operation speed at the maximum value defined by one of the speed levels (HI, HI2, MID, MID2, MID3, MID4, LO) after the operation speed reaches to the maximum value with the operation extent further increased. a prime mover; a hydraulic pump (P1, P2) to be driven by power of the prime mover to output operation fluid; a hydraulic actuator (C1-C4, C9, MR, ML, MT, AUX) to be actuated by the operation fluid outputted from the hydraulic pump (P1, P2); an operation member (19, 20) operated by an operator to change an operation extent of the operation member (19, 20); a first setting member for the operator to select one of revolution switching positions (R1-R7), each of the revolution switching positions (R1-R7) assigning a target value of the revolving speed of the prime mover; a second setting member for the operator to select one of speed switching positions (N1-N5); a storage portion to store a plurality of speed levels (HI, HI2, MID, MID2, MID3, MID4, LO), each of the speed levels (HI, HI2, MID, MID2, MID3, MID4, LO) defining a maximum value of operation speed of the hydraulic actuator (C1-C4, C9, MR, ML, MT, AUX) for a combination of selected one of the revolution switching positions (R1-R7) and selected one of the speed switching positions (N1-N5); a revolving speed controller portion configured to revolve the prime mover at the target value of the revolving speed assigned to selected one of the revolution switching positions (R1-R7); and a speed controller portion configured to increase the operation speed of the hydraulic actuator (C1-C4, C9, MR, ML, MT, AUX) as the operation extent of the operation member (19, 20) increases, and to maintain the operation speed at the maximum value defined by one of the speed levels (HI, HI2, MID, MID2, MID3, MID4, LO) after the operation speed reaches to the maximum value with the operation extent further increased.