Provided is a vehicle door lock device, including: a housing having an opening; a coupling member configured to be coupled to an operation mechanism arranged on a door; an operation lever arranged inside the housing and coupled to the coupling member through the opening; and a cover capable of opening and closing the opening and a coupling point between the coupling member and the operation lever. The cover is constructed separately from the housing and assembled to the housing so as to be mountable on and demountable from the housing and rotatable between an opened state and a closed state. Each of the housing and the cover includes: a temporary retaining mechanism configured to temporarily retain the cover in the opened state under a state in which the cover is assembled to the housing in a rotatable manner; and a full retaining mechanism configured to retain the cover in the closed state under the state in which the cover is assembled to the housing in a rotatable manner.