A wiper device includes: a pivot shaft that rotates back and forth within a predetermined angular range; an arm head that is fixed to the pivot shaft; a cover that is mounted to the arm head; and a wiper arm that is pivotally supported on the arm head to come into and out of contact with a surface to be wiped. The wiper arm includes an engagement concave portion that extends in a longitudinal direction of the wiper arm at a side portion in a pivot direction of the wiper arm. The cover includes an engagement convex portion that extends in the longitudinal direction of the wiper arm. Relative movement of the wiper arm and the cover is restricted by engagement between an engagement wall portion of the engagement concave portion and the engagement convex portion.