Short answer: No.

• For monks and nuns: Any sexual activity, including self‑stimulation, is absolutely prohibited under the Mahavrata of Brahmacharya.
• For lay Jains: The Anuvrata of Brahmacharya requires chastity and restraint. Masturbation is counted as unchaste self‑indulgence and is to be avoided. Both Digambar and Shvetambar traditions uphold this; wording in texts may vary, but the rule is the same.

Why: Jain Dharma teaches that sexual excitement (rati) inflames passions (kashaya), causes influx of karmas (asrava), and disturbs samyama (self‑control). Hence deliberate arousal—by body, speech, or thought—is discouraged. Involuntary events like nocturnal emission are treated differently from deliberate acts; keep purity of mind and conduct.

If you are a lay follower struggling with this:

• Strengthen Brahmacharya through samayik, pratikraman, paushadh, careful diet and company, limiting stimuli (media, idle talk), and remembering the Tirthankaras.
• If a lapse happens, do pratikraman sincerely and recommit to the vow.
• Seek guidance from a knowledgeable guru according to your tradition.

For a simple overview of vows, see: