[en] This paper discusses on the structure of the central bulge of the galaxy. A bright ellipsoidal part at the center of the galaxy was observed by the infrared observation in May, 1976. The obtained results were compared with the Miyamoto-Nagai model. The parameters a and b in the mass distribution given by this model were determined from the experimental results. The observed mass distributions in galaxy longitude and latitude were compared with the calculated ones. By using the obtained values of a and b, the mass of the bulge was estimated. The rotation of the center part of the galaxy is caused by the balance of the attractive force due to inside mass and centrifugal force. The observed velocity of the rotation was compared with the calculated values by the Miyamoto model assuming the mass of 2.8 x 10¹⁰ x solar mass. Agreement between the observation and the calculation is good for rotation velocity around 1 kpc. The mass to luminosity ratio was also obtained as 3.06. This value suggests that the center of galaxy is a little different from that of ordinary ellipsoid galaxy. Existence of a lot of giant stars is considered. The volume emissivity at 2.4 μm is shown as a function of distance. (Kato, T.)