An auxiliary mirror device for vehicles includes a fixation unit, a connection unit, and an auxiliary mirror. The fixation unit is adapted for coupling on a vehicle rear view mirror. The connection unit includes a connection rod coupled to the fixation unit, and a sleeve is engaged on the connection rod. A supporting rod disposed on the auxiliary mirror is received in the connection rod retractably. The connection unit further includes an adjustment barrel moveable relative to the sleeve and can be locked with of the sleeve. A tightening ring is engaged in the adjustment barrel and can be releasably compressed by the sleeve. A position of the auxiliary mirror relative to the side view mirror can be adjusted. When the auxiliary mirror is adjusted to a required position, the adjustment barrel can be operated for coupling and fixing the supporting rod and the connection rod together.