A locating device includes a guiding member, a sliding assembly and a pulling assembly. The guiding member includes a guiding space, and the sliding assembly includes a shaft part. The pulling assembly includes a pulling member, and the pulling member includes a sliding member inserted into the guiding space. An axis coupling part is disposed between the sliding member and the pulling member and pivotally connected to the shaft part. When the pulling member of the pulling assembly is operated to open or close, the sliding member is longitudinally moved in the guiding space to make the sliding assembly simultaneously move laterally, so as to form an open state or a closed state. As a result, a complicated assembly operation using screw for locking can be omitted, and the effect of decreasing whole operational difficulty and improving whole assembling speed can be achieved.