Thak you for help! But I want to put ErrorProvider in field of DataGridView! So I add: private void dataGridView_CellValidating(object sender, DataGridViewCellValidatingEventArgs e) { DataGridView dgv = sender as DataGridView; if (dgv.IsCurrentCellInEditMode) { dgv.Rows[e.RowIndex].Cells[0].ErrorText = "You made an error!"; } }