Abstract: An assembly block for a teaching material and a plaything ensures connection of wire lines at all possible link positions at which the assembly block is linked and in all possible link directions in which the assembly block is linked. Four link recess portions 12 are formed in a link surface 11a of an assembly block 10, and a round connector 13 is disposed at the center of the link surface 11a. Bottom plates of steel are disposed at the bottom of the link recess portions 12. Magnets are inserted inside the link recess portions 12 with the link recess portions 12 opposed with each other, whereby two assembly blocks are linked to each other. The connector 13, disposed for electrical connection with the connector 13 of another assembly block, comprises connection terminals which are disposed in a concentric arrangement on an insulation plate.