Worksheets("main").Sort.SortFields.Clear
Worksheets("main").Sort.SortFields.Add Key:=Range("C1"), _
    SortOn:=xlSortOnValues, Order:=xlAscending, DataOption:=xlSortNormal
With .Worksheets("main").Sort
    .SetRange Range("A2:G317")
    .Header = xlNo
    .MatchCase = False
    .Orientation = xlTopToBottom
    .SortMethod = xlPinYin
    .Apply
End With

'option explicit 入れましょう！念のためですが、初期設定は導入編でお伝えしたとおりにやっていますか？
'部分だけでなく、これらを呼び出す全体制御のマクロとも連動するところまで作ってみましょう。それで何度か動作確認したら、[*]の問題にも気づけたかも。
Sub GyoNarabekae2()

    Dim wsFm As Worksheet
    Dim cnt As Long
    Dim InFmMx As Long
    Set wsFm = Worksheets("main")
    InFmMx = Range("B" & Rows.Count).End(xlUp).Row

    wsFm.Range("A1").Value = "日付"

    '■■■■■Autorfillを使ってみる。
    '最低、2つのセルへの入力が必要です。以下だと、すべての行に値「1」が入ってしまいます。(excel2007で動作確認した場合) [*]
    With Range("A2")
        .Value = 1
        .AutoFill Destination:=Range("A2:A" & InFmMx)
    End With

    wsFm.Range("A1:G" & InFmMx).Sort Key1:=Range("B1"), _
                                     Order1:=xlAscending, _
                                     Header:=xlYes
End Sub

Sub Narabekae2() '通常の.sortで十分なのでノーコメントです。

'■並べ替えでAutofilterを使ってみる。

    Dim wsFm As Worksheet
    Dim InFmMx As Long
    Set wsFm = Worksheets("main")
    InFmMx = Range("B" & Rows.Count).End(xlUp).Row

    wsFm.AutoFilterMode = False
    wsFm.Range("A1").AutoFilter
    wsFm.Range("A1").AutoFilter.Sort.SortFields.Add Key:=Range("B1"), _
                                                    SortOn:=xlSortOnValues, _
                                                    Order:=xlAscending, _
                                                    DataOption:=xlSortTextAsNumbers
    With ActiveWorkbook.Worksheets("main").AutoFilter.Sort
        .Header = xlYes
        .MatchCase = False
        .Orientation = xlTopToBottom
        .SortMethod = xlPinYin
        .Apply
    End With
    Range("A1:A" & InFmMx).ClearContents

End Sub


Sub Keisen2() '↓よく書けていると思います v(^^*

'■sub keisennでSelectionを削除したマクロ
    Dim InFmMx As Long
    InFmMx = Range("B" & Rows.Count).End(xlUp).Row

    With Range("B16:K" & InFmMx)
        .Borders(xlDiagonalDown).LineStyle = xlNone
        .Borders(xlDiagonalUp).LineStyle = xlNone
        With .Borders(xlEdgeLeft)
            .LineStyle = xlContinuous
            .ColorIndex = 0
            .TintAndShade = 0
            .Weight = xlThin
        End With
        With .Borders(xlEdgeTop)
            .LineStyle = xlContinuous
            .ColorIndex = 0
            .TintAndShade = 0
            .Weight = xlThin
        End With
        With .Borders(xlEdgeBottom)
            .LineStyle = xlContinuous
            .ColorIndex = 0
            .TintAndShade = 0
            .Weight = xlThin
        End With
        With .Borders(xlEdgeRight)
            .LineStyle = xlContinuous
            .ColorIndex = 0
            .TintAndShade = 0
            .Weight = xlThin
        End With
        With .Borders(xlInsideVertical)
            .LineStyle = xlContinuous
            .ColorIndex = 0
            .TintAndShade = 0
            .Weight = xlThin
        End With
        With .Borders(xlInsideHorizontal)
            .LineStyle = xlContinuous
            .ColorIndex = 0
            .TintAndShade = 0
            .Weight = xlHairline
        End With
     End With
End Sub

Sub GyoModosu2()

    '■■■■■■■行を戻すマクロ
    Dim wsFm As Worksheet
    Dim InFmMx As Long
    Set wsFm = Worksheets("main")
    InFmMx = Range("B" & Rows.Count).End(xlUp).Row
    wsFm.Range("A1:G" & InFmMx).Sort Key1:=Range("A1"), _
                                     Order1:=xlAscending, _
                                     Header:=xlYes
    Range("A1:A" & InFmMx).ClearContents

End Sub