PURPOSE: To reduce falling-off of the filled activating substance and to obtain the substrate for an expansion-type storage battery which has an increased height and in which the filling amount of activating substance can be increased.

CONSTITUTION: The large V-shaped slit part 3a which is set in the interval 2 between the slits 3 and 3 of the contiguous slit line is formed in the middle part of each slit 3. When the elementary plate 1 having such slits 3 in zigzag form is pulled in the direction of width and each slit 3 is exapanded, a band-shaped substrate A for expansion-type storage battery is obtained where said substrate A is equipped with the protrusion 6 which protrudes outwardly from the base surface of the elementary plate and has a height h and the V-shaped inner surface 6a, at one corner part of the rhombic through window 5, namely at each cross point of lattice crosspieces 4 and equipped with a groove 7 having the V-shaped inner surface 7a at the other corner part opposite to the corner part described the above. Therefore, when the substrate A is filled with the activating substance in paste form, the contact area with the filled activating substance increases in comparison with the conventional rhombic through window 5 having a simple form, at the V-shaped inner surface 6a of the V-shaped protrusion 6 at one corner of each rhombic and at the through window 5 V-shaped inner surface 7a of the V-shaped groove 7 at the other corner, the close holding performance of the activating substance is increased to that extent, and falling-off can be prevented.