A solid state image sensor including a number of lateral type static induction transistors arranged in a matrix, sources of all transistors being commonly connected to ground potential, gates of transistors arranged in each row being commonly connected to respective row lines and drains of transistors arranged in each column commonly connected to respective column lines, a vertical scanning circuit connected to the row lines, a plurality of column selection transistors each connected between respective column lines and a video output line, and a horizontal scanning circuit connected to gates of the column selection transistors. After one row has been read out, photocarriers stored in transistors belonging to the relevant row are simultaneously discharged by means of a reset signal supplied from the vertical scanning circuit. Then any excessive amounts of photocarriers stored in the transistors are discharged away by means of clear signals supplied from the vertical scanning circuit every time transistors belonging to another row are reset.
Solid state image sensor having means to reset and clear static induction transistor photoelements