By the impedance probe (IMP) on board the Hinotori satellite, that was launched on February 21, 1981, into the semi-equatorial orbit with inclination of 31° and nearly constant altitude of 650km, data of electron density profiles along more than 1500 orbits have been obtained with an error less than ±3%. The detected profiles of electron density contain the data of the equatorial plasma bubbles. Preliminary statistic studies on the occurrence frequency indicate that there are at least three types of the plasma bubbles. The plasma bubbles that belong to the first type grow mainly from the evening to the midnight period with large depletion rates of electron density; since the depletion regions are sequencially aligned those are called here multiple plasma bubbles (MPB). The second type plasma bubbles are enhanced mainly after midnight, even in sunlit condition, with periodic features and are called here quasi periodic plasma bubbles (QPB). There is a third type of plasma bubble characterized by its solitary features called here solitary plasma bubble (SPB). The SPB phenomena takes place in all of the night time period. In the topside region of the ionosphere near the edge of the occurrence region of the plasma bubble, there frequently appear electron density enhancements with deviation of a few percent to the background electron density. These newly discovered phenomena are called here plasma blob. Occurrence characteristics of the plasma blob are also discussed.