Observation system, program, and method for controlling observation system

[Solution] Provided is an observation system for observing a sample lump that is formed by samples gathering together in a container containing the samples and a solution therein. The observation system includes: a collective imaging unit for imaging said the entire container; a sample lump identification unit for identifying a sample lump formed in the container from an entire observation image that is acquired by imaging said the entire container; a magnification imaging unit for magnifying and imaging a part of a region of the container including the sample lump identified by the sample lump identification unit; and a history information storage unit for storing the positional information of the sample lump in association with time and date information. While the sample lump identification unit performs a process of identifying said sample lump, the magnification imaging unit magnifies and images a part of the region of the container on the basis of the past positional information which is stored in the history information storage unit.