BACKREST OR SEAT OF CHAIR

摘要

PROBLEM TO BE SOLVED: To provide a high cushioning property and fitness in a simple structure in a backrest of a chair.SOLUTION: A backrest 5 includes a synthetic resin back plate 8. The back plate 8 includes left/right side members 19 and multiple horizontally-long support plates 22 for connecting the side members. Parts close to left/right both ends of the horizontally-long support plates are formed with narrow-width parts 27 as deformation facilitating buffer parts. The deformation facilitating buffer parts of the horizontally-long support plates 22 can be formed with swelling portions at left/right root parts, protruding forward from the side members 19. The deformation facilitating buffer parts have left/right-directional expanses. The deformation facilitating buffer parts are easily deformed so as to secure the high cushioning property and fitness. No stress concentration is formed on the backrest so as to improve the durability.