A sliding portion of a slider slides on a sliding surface of a base. This slider is biased toward the base by a stabilizer formed by an elastic, small-diameter, rod-shaped member. Specifically, the stabilizer is formed by a center portion, a link portion, a spring portion, and an abutting portion. When the abutting portion abuts an abutting recess of a cover attached over the slider to be biased toward the base, the spring portion plastically deforms about an arc portion. Due to a resulting reaction force, a pressing portion formed by the center portion biases the sliding portion of the slider toward the base. Accordingly, play may be suppressed with a small number of components.