As this is sometimes asked about, I’m sharing a current list of Samurai Museums or Museums with Samurai Exhibitions in Japan if you're searching for information on them. Also adding in some Japanese castles at the end with samurai collections or living spaces.
Please feel free to add others I may have missed in the comments.
Tokyo National Museum
Regular exhibition in the Japanese gallery has Arms and Armour of the Samurai in two rooms in their Honkan Japanese gallery (until July 5^(th)). The rooms include swords, armour helmets and a letter from Date Masamune (a famous Samurai and Daimyo in Tohoku). Admission: 1,000 yen for adults. Free for under 18 years old or over 70. University students: 500 yen.
Also they have a special exhibition until June 7^(th) for the Maeda family, a prosperous samurai family which ruled the Hokuriku area around Kanazawa. There’s a lot to see with swords, daggers, armour, but also art including calligraphy and tea ceremony related utensils. There’s an extra admission cost for this: 2,300 yen for adults, 1,300 for university students. Free for Junior High School age or below.
Access: 10 minute walk from Ueno station
Samurai Museum Shinjuku (Tokyo)
This was a museum close to Shinjuku Station with Katana swords and Samurai armour but unfortunately it’s been closed since the Covid-19 pandemic.
Samurai Ninja Museum Tokyo or Kyoto
More for those looking for an experience, there are 3 locations (2 in Tokyo and 1 in Kyoto). There are several experiences with the basic one being 60 minutes, where you have a guide that walks you through the samurai and ninja exhibits, then you have an opportunity to dress up in Samurai armour. There’s also a ninja experience where you learn about the weapons and tools and you can try throwing ninja stars after a training session.
Basic Ticket: 3,000 yen for adults and 2,700 yen for children under 12, and there are some small 10% discount codes available.
Asakusa Musuem (Tokyo) Access: 8 minutes from Asakusa Station
Shinjuku Museum (Tokyo) Access: 8 minutes from Shinjuku Station
Kyoto Museum Access: 7 minutes from Kawaramachi Station
The Japanese Sword Museum (Tokyo)
If you’re looking for swords specifically, this museum has exhibits that displays a wide range of swords. You can see Tachi, Katana, Wakizashi, and Tanto. Often you can see which are signed and in the current exhibition there are some by masters like Masamune. One thing to note is that between exhibitions, they are closed for about a week, so check the website before visiting. (Exhibition now runs until May 24^(th)).
Admission: Adult 1000 yen, Students 500 yen, and free for under 15 years old
Access: 7 minutes from Ryogoku Station’s West Exit.
Nagoya Touken World
So this is not in Tokyo but Nagoya, but worth the visit if you are in the city. They have an impressive collection of weapons, with 200 swords, 50 pieces of armour, and I was surprised to see their ukiyo-e works (150 pieces) went I went, along with the guns from the later periods. What’s really good is that several armour pieces are viewable in 360 degree stands, and they have several national treasures included in the collection.
Admission: Adults 1200 yen, Seniors 1000 yen, university and high school students 500 yen, and 300 yen for elementary and junior high school students. Free for children under six years old.
Access: 10 minute walk from Yabacho station.
Japanese Castles with Samurai Collections/ Living Spaces:
Matsumoto Castle: Has a collection of samurai matchlock guns and armour. Also, my personal favourite castle as its original and looks stunning.
Osaka Castle: This is not the original castle as reconstructed but has 8 floors with several focusing on the ruling samurai such as Toyotomi Hideyoshi who unified Japan at the end of the Sengoku period so good if you want to learn more about Samurai history.
Tsuruga Castle (Aizu Wakamatsu in Tohoku): Focuses on the civil war and samurai spirit but they have a good collection of swords and armour. Not being able to take photos kind of makes it more a precious experience.
Nagoya Castle: Built by Shogun Tokugawa Ieyasu, and the first Japanese castle to be designated a National Treasure. The main keep is under reconstruction, but the Honmaru Palace was recreated with decorative fittings and fine art works in the rooms and halls so you can see where the Shogun and key samurai families lived and worked.