A vehicle door lock device, comprising: a housing having an opening (52a1, 52a2) and being configured to be assembled to a door of a vehicle; a coupling member (61, 62) having a coupling portion and being configured to be coupled to an operation mechanism arranged on the door; an operation lever (21, 44) being arranged inside the housing and having a coupling portion coupled to the coupling portion of the coupling member (61, 62) through the opening (52a1, 52a2); and a cover capable of opening and closing the opening (52a1, 52a2) and a coupling point between the coupling member (61, 62) and the operation lever (21, 44), the cover being 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 comprising: a full retaining mechanism configured to retain the cover in the closed state relative to the housing under the state in which the cover is assembled to the housing in a rotatable manner; characterized in that each of the housing and the cover further comprising: a temporary retaining mechanism configured to temporarily retain the cover in the opened state relative to the housing so that the cover is at a predetermined rotation position under a state in which the cover is assembled to the housing in a rotatable manner. a housing having an opening (52a1, 52a2) and being configured to be assembled to a door of a vehicle; a coupling member (61, 62) having a coupling portion and being configured to be coupled to an operation mechanism arranged on the door; an operation lever (21, 44) being arranged inside the housing and having a coupling portion coupled to the coupling portion of the coupling member (61, 62) through the opening (52a1, 52a2); and a cover capable of opening and closing the opening (52a1, 52a2) and a coupling point between the coupling member (61, 62) and the operation lever (21, 44), the cover being 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 comprising: a full retaining mechanism configured to retain the cover in the closed state relative to the housing under the state in which the cover is assembled to the housing in a rotatable manner; characterized in that each of the housing and the cover further comprising: a temporary retaining mechanism configured to temporarily retain the cover in the opened state relative to the housing so that the cover is at a predetermined rotation position under a state in which the cover is assembled to the housing in a rotatable manner. a full retaining mechanism configured to retain the cover in the closed state relative to the housing under the state in which the cover is assembled to the housing in a rotatable manner; characterized in that each of the housing and the cover further comprising: a temporary retaining mechanism configured to temporarily retain the cover in the opened state relative to the housing so that the cover is at a predetermined rotation position under a state in which the cover is assembled to the housing in a rotatable manner. a temporary retaining mechanism configured to temporarily retain the cover in the opened state relative to the housing so that the cover is at a predetermined rotation position under a state in which the cover is assembled to the housing in a rotatable manner.