A stabilizer comprises housing, a lever, and a plate spring. The lever has a shaft, a main body extending radially from the shaft, an elongated portion extending at an angle from the main body, and a cam portion extending from the shaft in a substantially opposite direction to the main body. A tip of the elongated portion extends outward through an opening in the housing. The plate spring has a plane portion fixed to the housing, and a curved portion pushed by the lever cam portion. When the stabilizer is attached to a fixed member (case). The lever tip portion extends from the opening of the housing and abuts to the surface of a slide member (holder). The lever tip exerts a constant load to the surface of the slide member, even if the distance between the fixed member and the slide member changes.