A lock device includes a first bracket 34 fixed to a screw element 33 and formed with a lock hole 34b; a second bracket 35 which has a fitting portion 35a fitted to the turn-type control lever 30 of an operation pattern selecting valve 16 and which is formed with a lock hole 35f; and a lock 36. The screw element 33 is screwed into a threaded hole 32 formed in an end plate 29 of the operation pattern selecting valve 16 to secure the first bracket 34 to the end plate 29. The fitting portion 35a of the second bracket 35 is fitted to the turn-type control lever 30 to connect the second bracket 35 to the turn-type control lever 30. The lock 36 is insertably attached to the respective lock holes 34b and 35f of the first bracket 34 and second bracket 35 for locking the turn-type control lever 30. With such a structure, the lock device can be manufactured relatively easily without the necessity of processing the operation pattern selecting valve.