The l = -1 \fdg 2 region in the Galactic center has a high CO J =3–2/ J =1–0 intensity ratio and extremely broad velocity width . This paper reports the detection of five expanding shells in the l = -1 \fdg 2 region based on the CO J =1–0 , ^ { 13 } CO J =1–0 , CO J =3–2 , and SiO J =8–7 line data sets obtained with the Nobeyama Radio Observatory 45 m telescope and James Clerk Maxwell Telescope . The kinetic energy and expansion time of the expanding shells are estimated to be 10 ^ { 48.3 \mbox { - - } 50.8 } erg and 10 ^ { 4.7 \mbox { - - } 5.0 } yr , respectively . The origin of these expanding shells is discussed . The total kinetic energy of 10 ^ { 51 } erg and the typical expansion time of \sim 10 ^ { 5 } yr correspond to multiple supernova explosions at a rate of 10 ^ { -5 } – 10 ^ { -4 } yr ^ { -1 } . This indicates that the l = -1 \fdg 2 region may be a molecular bubble associated with an embedded massive star cluster , although the absence of an infrared counterpart makes this interpretation somewhat controversial . The expansion time of the shells increases as the Galactic longitude decreases , suggesting that the massive star cluster is moving from Galactic west to east with respect to the interacting molecular gas . We propose a model wherein the cluster is moving along the innermost x _ { 1 } orbit and the interacting gas collides with it from the Galactic eastern side .