We developed a prototype of mechatronic-system-embedded 'tsumiki' (building blocks) with a shape of 48mm cube consist of "ezomatsu (picea jezoensis)" material. The 'tsumiki' is one of the typical wooden toy, which consists of wooden blocks of various shapes, including cubes, pyramids, and cylinders. These blocks can be assembled, built, stacked, lined, or handled, in any way the player intends. The mechatronic system embedded in a 'tsumiki' is getting started to work with these natural playing motion. The mechatronic system is comped of a PIC processor, a CdS brightness sensor, a megnetic sensor, a tilt switch, four LEDs, a magnets and two CR2016 batteries to drive them, and it is incomporated in to a cube block. There is a holl at the center of each cube surface, instead of a surface that the magnet is settled in. The turn on/off motion of four LEDs are controlled by the PIC processor according to sensor conditions.