A pet leash device comprises a casing (10), a winding wheel (20), and a leash cord (30), and further comprises a locking mechanism. The locking mechanism includes a button (401), a manipulation member (402), a first spring (403), and a pawl member (404). The manipulation member (402) includes a transverse portion (4021) and a longitudinal portion (4022) which are connected in sequence. The lower portion of the button (401) is hingedly connected to the transverse portion (4021), and the longitudinal portion (4022) is hingedly connected to one end of the pawl member (404). The first spring (403) is located between the transverse portion (4021) and the wheel engaging portion (4041) of the pawl member (404). The winding wheel (20) is formed with a toothed groove (201) for the pawl member (404) to engage with when the button (401) is pressed. Inside the winding wheel (20), there is further provided a torsion spring for rotating the winding wheel (20) to retract the leash cord (30). After the button (401) is pressed, the pawl member (404) engages with the toothed groove on the winding wheel (20), such that the winding wheel (20) cannot rotate counterclockwise, meanwhile the torsion spring inside the winding wheel (20) recoils to rotate the winding wheel (20) clockwise, i.e., to retract the leash cord (30). When the button (401) is released, the button automatically recovers, i.e., returns to a free state, and at the same time the leash cord (30) can be pulled out.
