電子書籍リーダー 比較

How to choose an e-reader in 2026

E-readers remain a niche, deliberate device class. The Mars Score weights display, battery life, storage, and ecosystem (store, file-format support) most heavily. Backlight uniformity, page-turn latency, and water resistance are secondary but decisive when comparing siblings within one brand.

E Ink generation matters more than resolution

Carta 1200 and Carta 1300 panels deliver faster refresh and deeper blacks than the older Carta 1100 still shipping on budget Kindles. Resolution clusters around 300 ppi on premium models — visually indistinguishable from print at reading distance. Color e-ink (Kaleido 3, Gallery 3) trades ~20% resolution and contrast for color; the Kobo Libra Colour is the strongest mainstream implementation today.

Note-taking and stylus support

Kindle Scribe, Kobo Elipsa, and reMarkable target the same use case from different angles. Kindle Scribe is best for Amazon-bought books with handwritten margin notes; reMarkable is a pure note-taking tablet that happens to read PDFs well; Kobo Elipsa sits between the two.

Store lock-in is the biggest hidden cost

Kindles read .azw3/.kfx natively but require sideload conversion for ePub. Kobo and Boox read ePub natively and let you sideload Kindle content with effort. If you already have a large Amazon library, the friction cost of switching often outweighs hardware advantages.

Battery life is measured in weeks

Modern e-readers claim 6–12 weeks of battery life on a charge. Real-world numbers depend on wireless usage and warm-light backlight. Look at our Mars Labs sustained-use measurements rather than manufacturer figures.

Waterproofing and ergonomics

IPX8 (1 meter for 60 minutes) is now standard on premium e-readers. Weight ranges from 175g (Paperwhite) to 433g (Kindle Scribe); for one-handed reading, look hard at sub-200g devices.

How vsMars scores e-readers

Each Mars Score combines display generation/resolution, storage, battery life, water rating, and ecosystem flexibility per the public methodology. See tablets if you want a single device for reading plus general use, and Buyer's Guides for use-case shortlists.