NOVELTY - A cylindrical culture tank (1) has a top wall provided with culture-solution inlet opening. A heater (17) arranged at inner face of lower portion of side wall of the tank, maintains the culture solution in the tank, at a preset temperature. A rotary shaft (12) bearing a stirring blade (11) for stirring the culture solution, is suspended from the center of the top wall.    USE - The apparatus is useful for performing culture of useful microorganisms used for improving soil quality, composting of organic refuse, decomposition of bad odor, and purification of river.    ADVANTAGE - Enables uniformly and efficiently heating the culture solution as the stirring blade arranged above the heater, stirs the solution which is heated by the heater arranged at lower portion of the tank. Enables adjusting the temperature of the heater, based on the output of the detector. Prevents entry of dust and harmful microbes into the tank as the level of the solution in the tank can be confirmed, without opening the lid of the tank, and as the exhaust pipe is shaped suitably. Improves the operability of the apparatus by positioning the controller near the inlet opening. Prevents excessive increase of pressure inside the tank, by provision of the exhaust pipe. Enables easily moving the tank, to the desired location, during maintenance and cleaning.    DETAILED DESCRIPTION - A temperature detector is arranged at the inner face of lower portion of the side wall of the tank, at the position opposing the heater, to detect the temperature of the culture solution. A gauge for confirming the quantity of culture solution in the tank, is provided at the outer peripheral surface of the tank. An inverted-U-shaped exhaust pipe (14) has a non-return valve capable of being opened outwardly, provided at the front-end opening. The exhaust pipe is provided in the top wall. The caster-mounted base of the apparatus, which supports the tank, has a horizontal rod from which a vertical rod supporting a controller for controlling the heater and the stirring blade is extended. The controller is arranged near the inlet opening. A stopper provided in the outer peripheral face of lower portion of the tank, melts when the interior temperature of the tank reaches a preset value, and forcedly ejects the culture solution.    DESCRIPTION OF DRAWING(S) - The figure shows a front view of a culture apparatus.    Tank (1)    Stirring blade (11)    Shaft (12)    Heater (17)    Exhaust pipe (14)