Composition and a cured product containing a silicon-containing polymer

The present invention includes (A) and structural units represented by the following general formula (1) (A1), and a structural unit (A2) represented by the following general formula (2), the structural units (A1) the weight ratio of the portion constituted by the formed part and the structural unit (A2) ((A1) :( A2)) is 4: 96 to 70: 30 and silicon-containing polymer is a curing agent (B) is a composition characterized by containing. [Formula 1] [In the general formula (1), R ] [Formula 2] [In the general formula (2), R According] to the composition of the present invention, gas barrier properties, high adhesion to the organic substrate and is capable of forming a cured product of a thick film, the cured product is suitably used as a LED encapsulating agent be able to.