The swing arm suspension has such a structure that a pivot plate (8) is provided with a pivot shaft (11), a swing arm (13) having a rear end portion supporting a rear wheel (12) is swingably mounted at a front end portion to the pivot shaft (11), and a cushion unit (14) is mounted at an upper end portion to the swing arm (13) and connected at a lower end portion through a link mechanism (15) to a portion of the pivot plate (8) lower in level than the pivot shaft (11). In this swing arm suspension, an upper portion of the swing arm is provided with an exposing portion (80A) for exposing a cushion arrangement space H to an upper space K above the swing arm (13). At least one of a subtank (57) and an adjuster (56) as functional components of the cushion unit (14) is located in the exposing portion (80A).