The shift response in a V-belt type automatic transmission is improved using a double cogged V-belt having an endless core wire embedded portion in which core wires are embedded, a lower cog formed portion provided over the inner circumference of the core wire embedded portion, and an upper cog formed portion provided over the outer circumference of the core wire embedded portion, as a V-belt for transmitting power from a drive pulley device to a driven pulley device. Each of the core wires is formed from aramid fibers, and the ratio (W/T) of the width W of the V-belt to the thickness T of the V-belt is set to 2.5 or less.