A splice joint of a main girder of a crane, the main girder including at least two longitudinal main girder parts to be connected to each other by their ends and each having a central web which includes at least one web plate, longitudinal upper and lower flanges, the lower flange protruding from the central web to both sides thereof. The splice joint includes a plate-like tongue-and-groove joint, the tongue-and-groove joint including a tongue fixed to the central web of a main girder part, and a groove fixed to the central web of a second main girder part; and a lower flange joint receiving the bending forces of the splice joint. The tongue-and-groove joints are arranged reversed in relation to each other, and the location of the tongues and grooves on opposite sides of the web is reverse in relation to each other.