A profile gauge contains: a body, a holding plate, a plurality of slidable measuring members, and a locking assembly. The body is formed in an elongated plate shape and includes an accommodating chamber defined thereon and two ruling portions parallelly arranged on two sides of the accommodating chamber, wherein each ruling portion has a graduation for measuring a distance between two points of a profile curve line of an object. The holding plate is rectangular and includes an insertion extending outwardly from a first end thereof and an extension extending outwardly from a second end thereof. Each slidable measuring member includes a fixed thickness and an elongated aperture defined thereon, wherein a width of the elongated aperture is more than a width between the two sides of the holding plate. The locking assembly is fixed on the extension to limit a slidable movement of each slidable measuring member.