All official holidays in Finland are established by acts of Parliament.
（フィンランドの全公式休日は国会の条例 <議決> により定められます。）
The official holidays can be divided into Christian and non-Christian holidays.
(公式休日はキリスト教による休日と そうでないものに分けられます。）
The main Christian holidays are Christmas, New Year's Day, Epiphany, Easter, Ascension day, Pentecost, Midsummer Day, and All Saints' Day.
（キリスト教の休日のうち主なものは、クリスマス、元旦、公現日、復活祭、昇天祭，五旬節、聖ヨハネ祭、および　諸聖人の日です。）
The non-christian holidays are May Day and the Independence Day of Finland.
（キリスト教の休日以外のものには、メーデー、フィンランドの独立記念日があります。）

In addition to this all Sundays are official holidays but they are not as important as the special holidays. The names of the Sundays follow the liturgical calendar and they can be categorized as Christian holidays. When, in the late 1960s, the standard working week in Finland was reduced to 40 hours by an act of Parliament, it also meant that all Saturdays became a sort of de facto public holidays, though not official ones. Easter Sunday and Pentecost are Sundays that form part of a main holiday and they are preceded by a kind of special Saturdays.

Several Christian holidays traditionally falling on working days or on fixed dates have been moved to Saturdays and Sundays. In 1955, Midsummer day was moved to the Saturday following 19 June, the feast of the Annunciation to the Sunday following 21 March (or, if this coincides with Easter or with Palm Sunday, the Sunday before Palm Sunday), and All Saints' Day to the Saturday following 30 October. More holidays were moved in 1973: Epiphany to the Saturday following 5 January and Ascension Day to the Saturday before the traditional Thursday, but these revisions were reversed in 1991.

Tradition

Christmas Eve and Midsummer Eve might very well be the single most important holidays during the entire year for Finns. Surprisingly they are not officially called holidays and are not so marked in calendars, but for most people, they are not working days, and in practice they differ from official holidays only in that most shops are open on those days from early morning to 1 PM. They hold this de facto status partly due to some statements in legislation but also because most employment contracts provides for these days as full holidays. A number of the less important main holidays are also preceded by de facto half days, meaning that in some (but not all) offices working hours are then shorter than normally. These are Maundy Thursday, the day before May Day and New Year's Eve
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(★ ２０１５年１１月１３日：上記文章が気になったので、この文章の大意の訳文を緊急追加することにしました！
クリスマスイブ と 真夏祭イブ（＝夏至祭イブ） の２日は、フィンランド人にとっては、一年の中で一番重要な休日です。　しかも、こんな事を言ったら読者の皆様は更に驚かれると思いますが、イブの日は公式的には祝日とは呼ばれておりませんし、カレンダーにも休日としては記載されておりません。しかし、殆どの人達は、これらの日には仕事を致しません。そして更に、このイブの日が実生活に於いて他の休日と違っているのは、このイブの日には、お店屋さんだけは朝から昼過ぎの１時くらいまでの間は開いているのです。それは、どうしてかと言いますと、一部の文章には慣例的に開店日として記されてはいますが、殆どの就業規則では、まる一日の終日休業日として記されているからです。　これ等の２日のイブの他にも、この２日ほど重要ではありませんが、同じ様に、一部の仕事場では慣例的に労働時間が短い前夜祭的イブが先行しているメイデーの前日と昇天祭の前日と大晦日の休日があります。）

Already before the 5 days working week was generally adopted in Finland in the late 1960s, working hours in most cases were shorter on Saturdays (4...5 h) than on other weekdays (8 h), but they were equally shorter also on all eves of public holidays, for example on the eve of Epiphany, the eve of All Saints' Day, and even including Christmas Eve and Midsummer Eve. But when Saturdays ceased to be working days, new contracts removed these shortenings from other holiday eves, except from Midsummer and Christmas Eve which also became de facto holidays.

The Finnish calendar also provides for special flag days. A day's status as a flag day has no formal link with an eventual status as an official or as a de facto holiday. However, May Day, Midsummer Day and Indepence Day have both the status of a flag day and a public holiday.

Finland has an official National Day, December 6. Some minor observances are also denoted in the Finnish calendar, though they have not been judged worthy of either holiday or flag day status.