コピペVBAコード 

Sub TransformData()
    Dim inputSheet As Worksheet
    Dim outputSheet As Worksheet
    Dim lastRow As Long
    Dim outputRow As Long
    Dim outputCol As Long
    Dim key As String
    Dim dict As Object
    Dim i As Long

    ' シートを設定
    Set inputSheet = ThisWorkbook.Sheets("入力")
    Set outputSheet = ThisWorkbook.Sheets("結果")
    
    ' 結果シートをクリア
    outputSheet.Cells.Clear
    
    ' キーを保持するための辞書を作成
    Set dict = CreateObject("Scripting.Dictionary")
    
    ' 入力シートの最終行を取得
    lastRow = inputSheet.Cells(inputSheet.Rows.Count, "A").End(xlUp).Row
    
    ' 入力シートをループ
    For i = 1 To lastRow
        key = inputSheet.Cells(i, 1).Value
        ' キーが辞書に存在しない場合、追加
        If Not dict.exists(key) Then
            dict.Add key, dict.Count + 1
            outputRow = dict(key)
            outputSheet.Cells(outputRow, 1).Value = key
            outputCol = 2
        Else
            outputRow = dict(key)
            outputCol = outputSheet.Cells(outputRow, Columns.Count).End(xlToLeft).Column + 1
        End If
        
        ' B列以降のデータを出力シートにコピー
        Dim j As Long
        For j = 2 To inputSheet.Cells(i, Columns.Count).End(xlToLeft).Column
            outputSheet.Cells(outputRow, outputCol).Value = inputSheet.Cells(i, j).Value
            outputCol = outputCol + 1
        Next j
    Next i
End Sub