To provide a connection structure of a column and a beam in a wooden building that can easily and rigidly connect structural members such as a wooden sill, column and beam, and to provide a method of assembling the column and beam in the wooden building.

In the connection structure of the column and beam in the wooden building, a connecting metal fitting 40 for the wooden building has two fixing members 50 opposedly arranged in L-shaped cross section and having sidewalls that can cover the outer surface of the column 14 of square cross section, and beam fixing plates 52 extending in a perpendicular direction along the outer surface of the sidewalls of the fixing members 50. The connecting metal fitting 40 is mounted to the column 14 to cover the outer surface of the column 14 with the fixing members 50, and the beams 38 each provided at one end with a groove 54 to which a beam fixing plate 52 is fittable are mounted to the connecting metal fitting 40 so that the beam fixing plates 52 are fitted to the grooves 54. Fixing between the internal wall surface of the groove and the beam fixing plate 52, and between the end face of the beam 38 and the sidewall of the connecting metal fitting 40 is performed using an adhesive.