A vehicular interior rearview mirror assembly includes a mirror head, a mounting member configured to mount at an interior portion of a vehicle, and an attachment member having a connecting portion, a flange, a neck and a pivot element. The attachment member includes a conical portion that tapers from the flange portion toward the neck of the attachment member. The pivot element is disposed at an opposite end of the neck from the conical portion. With the attachment member disposed at a lower portion of the mounting member, and with the connecting portion received in and secured at a receiving portion of the mounting member, the flange abuts an end of the lower portion of the mounting member and an outer surface of the conical portion corresponds with an outer surface of the lower portion of the mounting member. The mirror head is adjustably attached at the pivot element.