To provide a portable holder for an interdental brush, in which the interdental brush comprising a linear brush part integrated with a stick-shaped handle part is normally usable in an existing form, and two interdental brushes can be held in a pair without increasing cost.

The device includes an inner cylinder 10 for detachably holding the two interdental brushes 1 and 2 in a pair by their handle parts 1b and 2b, and an outer cylinder part 20 to house the whole length of the interdental brushes 1 and 2 including the part held by the inner cylinder 10. A slit 22 is provided in a cylinder surface of the outer cylinder 20, with such a length that respective brush parts 1a and 2a are alternately and selectively put in and out through openings of the outer cylinder 20 and a movable lug 30 is integrally provided with the inner cylinder 10 to be inserted and placed inside the slit 22 on the outer cylinder 20.