Air bag apparatus for motorcycle

In order to provide an air bag apparatus corresponding to the motions found in motorcycle accidents, in an air bag apparatus (111) having an air bag (121) and provided on a motorcycle (100), the air bag (121) includes a first expansion part (123) which is expanded toward a rider protection region (151) which is formed above a body constituent part of the motorcycle (100) and in front of the motorcycle rider in the case of the forward collision of the motorcycle (100); and a second expansion part (125) which is expanded toward a rider protection region at pitching (153) which is formed in front of the motorcycle rider (101) in the pitching of the motorcycle (100) around a front wheel (141) due to the forward collision of the motorcycle (100).