An operation unit includes a case and an operation member molded integrally through injection molding. The operation member includes an outer surface and a slide portion supported by the case. The slide portion is slidable and movable relative to the case. The operation member further includes a knob operated by an operator, a parting line formed continuously from the slide portion to the knob along the outer surface, and a ridge line formed on the outer surface. At least part of the parting line is formed along the ridge line.